Am I Shoveling Sh!# Against The Tide ? Help !

[notsoMRWizard]

Hello, this is my first post so please bare with and be gentle.

I have a 13X21 Vinyl bladder above ground pool. It's been up for 4 years. I have usually had some sort of algea problem at the opening in spring but always managed to get it in check. Not so this year.

I opened the pool to a nice green moat color. I didn't test the water at that time. Dumb I know. I proceeded to add 3 or 4 shock paks over a two day period. (Calcium Hypochlorite) BAD, I know now. The green went away. The water then became cloudy. Maybe 12 to 18 inch visibility. So I then proceeded to add 5 lbs of PH +, 3 lbs stabalizer thinking that would hold the chlorine shock level up and filled my floater with 3 - 3 inch trichlor tabs.After a week, I still had cloudy water. So I then figured I'd better test the water. Obviously I waited to long to make that decision. Here are my first readings that I can recall.

FC = ?

TC = .5

PH = 6.8

ALK = 220

CH = ?

Cya = ?

So I started slowly adding PH minus and aerated the water to lower the ALK. I added maybe 4 lbs.

I know I waited way to long to investigate my situation, so I hope someone can help fix what I created ...

lets continue ...

Purchased Taylor #2004b test kit. Here were first numbers with the new kit ...

FC = 0

TC = .5

PH = 7.0

ALK = 190

CH = 500 (I think this is my problem)

CYA = off the chart (half way between base of tester and 100, lets say 200)

So I did some reasearch and came to the conclusion I'm an idiot, and also it looked like my best option was partial drain. I drained less than half but far more than a third of the water, and refilled. Fill water CH was 150. Removed the floater. when water level was back up I tested again ...

FC = 0

TC = 0

PH = 7.2

ALK = 175 (144 using Taylor Cyanuric Acid Correction to Total Alk)

CH = 500

CYA = maybe 120 (still over 100 mark but not by much)

So I waited untill the sun went down and added 4 Gal 60% bleach.

This morning pool is obviously still cloudy, here are the new numbers ...

FC = 10

TC = 15

CC = 5

PH = 7.4

ALK = ??? test went orange(maybe bleached out) so I am guessing around 170 still, that was when it turned)

CH = 500 ? didnt recheck

CYA = didnt recheck ...

Added 2 more gals of 60% bleach before the sun came up .....

NOW ..... Am I wasting my time with a CH of 500 ? and a CYA so high. When pool was draining I got in to do some cleaning and notice calcium build-up on the sides of the vinyl. Some areas were heavy. I was able to remove some of it with Hydrochloric/phosphoric acid cleaner , but couldnt get it off all the way down between the texture of the vinyl. So basically the whole pool has scale developed on the sides. Not really visible when wet but you can see it when it is dry.

I know I need to get the FC up to 20-25 for shock.

First is that possible with such a high cya?

Second with a CH of 500 what can I do ? Is the water TDS maxed out maybe. I have put more Chems in the pool so far this year than the last 2 combined.

Lastly ... Am I on the right track now ? Just keep adding bleach and hope the cloudy is algea and not calcium?

I'm really not looking forward to a full drain of the water but I'm also not interested in spedning the whole summer shoveling S#!T against the tide.

Any advise and info will be GREATLY appreciated.

THANX

[notsoMRWizard]

Update .... 2 hours later .... water check ...

FC = 30

TC = 30

PH = 7.4

seems like they should be different, but then I am using a 6x dillution with tap water and its still over 5 on my tester ....

[poolyeti]

Hi wizard,

With a CYA over 100 and CH around 500, I would really just lose some more water. Even if you could get everything balanced back out, your chlorine demand would be freakish.

[chem geek]

Hi wizard,

With a CYA over 100 and CH around 500, I would really just lose some more water. Even if you could get everything balanced back out, your chlorine demand would be freakish.

Ditto to the above. You should check the CH of your fill water since a partial drain/refill will certainly lower the CYA, but may not do much for the CH if the fill water is very high in CH. If it is, then you'll have to run your pool at lower TA and pH to prevent scaling and should use a pool cover, if possible, to limit evaporation which over time will just have CH increase.

Going forward, remember these simple rules:

For every 10 ppm Free Chlorine (FC) added by Trichlor pucks/tabs, they also add 6 ppm to Cyanuric Acid (CYA).

For every 10 ppm FC added by Dichlor granules/powder, it also adds 9 ppm to CYA.

For every 10 ppm FC added by Cal-Hypo, it also adds 7 ppm to Calcium Hardness (CH).

Using chlorinating liquid or unscented bleach will not increase CYA nor CH so once your CYA and CH levels are where you want them, you should use these unstabilized chlorine products instead of the stabilized or calcium ones above (Trichlor, Dichlor, Cal-Hypo).

Richard

[PaP dude]

I pretty much agree with all of the above. Another thing to keep in mind is that your filter (sand, cartridge, or DE) is going to be doing all the work to pull out the dead algae. Depending on what type of filter you have and your plumbing situation, you have a few options. While there is visible algae in your water, I would recommend trying to bypass your filter until all the algae is dead. (This will bring you to the cloudy stage) At this point you can "filter" out all the dead algae more efficiently. If you have a waste line, you can use a flocculant to settle everything to bottom and then manually vacuum everything directly out of your pool. (This will also help you too drop you CYA and CH levels.) This works well for above ground pools because of poor circulation. (Usually one or two return jets, one skimmer and no bottom drain) I hope these things help you out. Also, always remember your water chemistry! Vinyl lined pools tend to get out of wack a lot faster then a maricite pool. It is quite possible for your pH to be lower than a 6.8 when you test it. Phenol red can only test in the range 6.8 - 8.2. (assuming that is what you are using to test your pH) Although only "slightly acidic," you will find your equipment will corrode rapidly by keeping the pH low.

[notsoMRWizard]

Thanx for the advice. Ive added 8 gals of bleach since my first post. CC is still at 0. FC is above 20. I can see the bottom now. It's 100 % better, but only 50% clear. If I drain I guess I need to drain it all then. I already drained half and it didnt lower the cya near enough. The CH of the fill water is 150. I only have a simple filter setup, no backwash or anything. I should be cleaning the filter each day to remove dead algea and keep water moving correct. By freakish, do you mean unsafe, or just balanced at an alarmingly high level. I will probably drain this weekend but if the CC stays at 0 doesnt that mean the chlorine is ok and working, not just burning up ? a few gals of liquid chlorine each week doesnt seem to bad.

[poolyeti]

By freakish, do you mean unsafe, or just balanced at an alarmingly high level. I will probably drain this weekend but if the CC stays at 0 doesnt that mean the chlorine is ok and working, not just burning up ? a few gals of liquid chlorine each week doesnt seem to bad.

I'd need an assist from Richard, but I would probably say both.

Regarding the CC, with you CYA as high as it is, it's possible that you would need so much FC to keep the CC down that it could end up bleaching out the reagents.

As far as usage is concerned, I'm having to guess on your gallonage, but I estimate that you shouldn't be using more than a gallon and a half of chlorine per week. We typically suggest that customers add 1 quart of 12.5-15% chlorine per 10,000 gal every night. I'm estimating that your pool has something like 6500 gallons, which would make just a tad over a pint a night.

[chem geek]

When the CYA is really high, then a partial drain/refill to dilute its level makes later chemical adjustments much easier as you won't need really high FC levels. You can operate at high CYA levels by having much higher FC levels and/or use of supplemental algaecide, but getting the CYA at least below 80 ppm will make pool operation a lot easier. To prevent algae growth in manually dosed (non-SWG) pools, you need a minimum FC level that is at least 7.5% of the CYA level (this rule works up to a phosphate level of around 3000 ppb which is very high). So with a CYA of, say, 150 ppm, you would need to maintain an FC of at least 11.2 ppm unless you used a supplemental algaecide (PolyQuat 60 or a phosphate remover).

The effective chlorine concentration is proportional to the ratio of FC to CYA so having a high CYA and a correspondingly high FC is not unsafe. The FC by itself is only a factor if you were to drink the water. For swimming in it, it is the FC/CYA ratio that matters as that determines the disinfecting/oxidizing chlorine (hypochlorous acid) level and therefore its corresponding rate of reaction. Technically speaking, a pool with 150 ppm CYA and 11 ppm FC is roughly equivalent to a pool with 40 ppm CYA and 3 ppm FC.

Richard

[notsoMRWizard]

Could the cloudy water be a Phosphate issue ?? I had a large quantity of leaves in the pool which stayed for a good part of the winter. I have a fruitless mulberry with a 40 ft canopy, and I would say 60 % of the leaves ended up in the pool. I was unaware they were there as the pool was covered after the wind had blown and no one told me it was full of leaves. At least a good inch across the entire bottom. They were there long enough I think they started decomposing. Soft and very gooey. Could that have fed the algea bloom and added to the moat, and could the phophates be high ? Is there any way to test for phosphates ? Pool is a little clearer, mostly on the sides it seems. I did forget to metion the color purple. The sides were covered with purple after all the initial shocking and chemical additions. I assume thats just dead algea ?

[chem geek]

There are many possible causes for water to be cloudy, but in your situation it sounds like the cloudiness is dead algae and may also be a combination of too high a CH and TA as that causes both cloudiness and scale. As for the purple, that is not algae, but most likely copper cyanurate caused by a combination of high CYA levels, high pH (from shocking with hypochlorite sources of chlorine such as Cal-Hypo) and high levels of copper. I don't know where the copper came from -- possibly from an algaecide you used (did you use any sort of algaecide product -- does it contain copper?).

Since you have high CH and high TA, I suggest you test your fill water for CH and TA and unless these are high, you should do a partial drain/refill. This will also lower your CYA level so it's the easiest way to solve multiple problems at the same time. After you've done that -- say, a half drain/refill (possibly done through multiple drain/refill or continuous drain/refill), then you can measure again and see where things are at.

In the future, you should not use Cal-Hypo if your CH is already normal or high as every 10 ppm FC added by Cal-Hypo adds 7 ppm to CH. Also, you should not continue to use Trichlor tabs if your CYA is already normal or high as every 10 ppm FC added by Trichlor adds 6 ppm to CYA. Finally, if you see any chlorine product that says Dichlor, you should not use it if your CYA is already normal or high as every 10 ppm FC added by Dichlor adds 9 ppm to CYA.

Do not worry about the phosphates level -- they just contribute to algae growth as algae food but algae can be kept away with chlorine alone. If for whatever reason you don't want to manage your pool's CYA level through the use of unstabilized chlorine products (i.e. chlorinating liquid or unscented bleach), then when the CYA rises (from use of Trichlor or Dichlor) you must either raise the FC level or must use an algaecide (PolyQuat 60 or a phosphate remover). Those are your choices with the former being less expensive, but possibly less convenient, then the latter.

Richard

[notsoMRWizard]

My BAD !! ..... It seems in all the info I tried to give you all, I forgot to mention the Algecide. I added the Algecide after the initial shock with Cal-Hypo and after the addition of the stabalizer. I added 16 oz / per 10,000 gals. Active ingredient 11.83% Copper Sulfate Pentahydrate* ... * Copper as elemntal from triethanolamine complex:3.03%

If for whatever reason you don't want to manage your pool's CYA level through the use of unstabilized chlorine products (i.e. chlorinating liquid or unscented bleach), then when the CYA rises (from use of Trichlor or Dichlor) you must either raise the FC level or must use an algaecide (PolyQuat 60 or a phosphate remover). Those are your choices with the former being less expensive, but possibly less convenient, then the latter.

Does this mean the Algecide can lower the cya ?

Latest test results

FC = 20

TC = 25

CC = 5

PH = 7.4

ALK = 150

CH = 650

CYA = 110

ALK and CYA have dropped quite a bit since the first test. I dont get why the CH keeps going up. The fill water on the partial drain was 150. I did scrub the sides while it was refilling with Hydrochloric acid to try and remove some of the scale. Would that just transfer the calcium from the side of the pool into the water and dissolve, to raise the CH. Would the high chlorine level be bleaching out the test ? I am doing the High CH test (x25) from my kit. Could that be less precise ?

[chem geek]

Does this mean the Algecide can lower the cya ?

ALK and CYA have dropped quite a bit since the first test. I dont get why the CH keeps going up. The fill water on the partial drain was 150. I did scrub the sides while it was refilling with Hydrochloric acid to try and remove some of the scale. Would that just transfer the calcium from the side of the pool into the water and dissolve, to raise the CH. Would the high chlorine level be bleaching out the test ? I am doing the High CH test (x25) from my kit. Could that be less precise ?

Well, at least we now know where the copper came from. Yikes! You really need to do a partial drain/refill because you not only have too much TA, CH and CYA, but also have copper. If you still have too much copper leftover, you'll need to add a metal sequestrant, but one thing at a time. Keep doing more dilution (partial drain/refill).

The PolyQuat 60 algaecide or a phosphate remover will not lower the CYA, but they will help prevent the algae from growing so that it won't take as much chlorine relative to CYA to do so. You can look at the algaecide or phosphate remover as supplementing or helping the chlorine, but the higher CYA still makes the chlorine less effective than it would be if the CYA were lower. Such supplemental solutions aren't cheap, but they are an alternative.

As for the scale removal, yes dissolving that is dissolving calcium carbonate so that would cause the CH to climb and the TA and pH as well, but I doubt it was enough to have a serious effect on the numbers. Nevertheless, that is possible. I would just keep doing the partial drain/refill since the CYA is still high as is the CH and TA. You said your pool was 13x21 but didn't say how deep -- if it's 4 feet, then that's about 8200 gallons. A change of CH of 100 ppm in that sized pool would be almost 7 pounds of calcium carbonate -- that sounds like a lot unless you had a whole lot of scale.

By the way, the pH test won't be accurate when the FC is so high, though it would normally measure too high in that case. Perhaps the acid you are using has kept the pH down. When the FC drops eventually, you may find the pH dropping with it.

Also, you have to be extraordinarily careful using acid to dissolve scale on vinyl. Acid (low pH) is very detrimental to vinyl so it has to be very dilute, used very briefly to remove the scale, then rinsed off right away. It may be very hard to do properly so I hope no damage was done to the vinyl.

Finally, when you add chlorine to your pool, you should do so slowly over a return flow with the pump running. That prevents it from settling to the bottom. For extra safety, you can brush the area under where you add it.

In the future, next time you want to open your pool for the season, all you need is chlorine (and cleaning out physical mater from the pool, brushing the sides, and cleaning the filter). See this post that shows an algae filled pool opened in the spring using unstabilized chlorine (chlorinating liquid or unscented bleach) alone.

Richard

[notsoMRWizard]

Thanx for all the info Richard. I think i am going to drain the pool completely. Or at least 3/4 since the half drain I did already has had little to no effect. The water level is around 44 in. When I was using the acid to remove the scale I just applied to a small section from the waterline up, scrubbed, then rinsed and scrubbed more. All rinsing with pool water. Honestly other than lightening up the dirty bathtub water line the acid had little to no effect on the calcium deposits.

I guess my next question would be what one, or combonation of things would cause the CH to get that high. I have used Trichlor tabs since the day I started up the pool. As well as Sodium Dichlor and Cal Hypo for shock. I have never done more than a evap refill to the water. Could the TDS just be maxxed out?

I have only three things in my pool supply now. Ultra Bleach (60% unscented), AH Baking Soda, 20 Mule team Borax.

Again, thanx for helping all the numbers make sence.

-Chuck

[chem geek]

Chuck,

The Trichlor, Dichlor and Cal-Hypo are the answer to your question of how the Cyanuric Acid (CYA) and Calcium Hardness (CH) levels got so high. The pool store, or the bottle labels, should have told you the following, but for whatever reason they don't:

For every 10 ppm FC that you add with Trichlor, it also adds 6 ppm to CYA.

For every 10 ppm FC that you add with Dichlor, it also adds 9 ppm to CYA.

For every 10 ppm FC that you add with Cal-Hypo, it also adds 7 ppm to CH.

Unlike FC which gets used up every day, the CYA and CH just build up unless there is water dilution (and evaporation does not cause dilution -- only splash-out, backwash, or other physical water removal followed by refill causes dilution). Also, evaporation and refill simply adds the TA and CH content of the fill water to the pool so that can cause these to rise over time as well.

I assume you had a typo and the bleach was 6%, not 60%.

Take a look at this link and find the pan evaporation rate for your area. The numbers are inches of evaporation per year. Say that you are in an area with 70" evaporation per year. That's almost 6 feet so would be more than one full pool water volume. If your fill water had 150 ppm CH, then this means that your pool would increase in CH by more than 150 ppm over a year. In your case, I'm sure the Cal-Hypo was a significant contributing factor to the increase in CH as well.

Richard

[chem geek]

(deleting duplicate post...I hate the fact that this forum gets so darn slow and unresponsive and returns blank screens sometimes!)

[notsoMRWizard]

Ok .... Mission accomplished !!

Refill complete. 98% water change. I left 2 inches.

Ok so now its a fresh start. minus any algea. Is there a particular link I can goto for startup, or just give me a quick rundown on which process I should do first.

Here are the morning numbers. Fill was completed at MIdnight.

FC = .5

TC = 1.5

CC = 1

PH = 8.0

TA = 130

CH = 175

Cya = 0

Now will those numbers change rapidly as things settle, or should I just make adjustments right away ?

PH is high, TA is kinda high.

So it looks like I need to add Muriatic Acid to lower PH and ALK. Add Cya to 40 ppm. Then do an intial shock to raise the chlorine level.

Help me understand and differentiate here ...

According to my TAylor booklet ..

To lower TA I should add 2 qt Muratic acid. To lower PH I should add 1.15 qt.

Now when I add Cya the CYAf says that the TA should drop to 100. That tells me go with the lower amount of Muratic acid.

To get CYA to 40 i need to add 4 lbs.

Now as for the Bleach. I am going to use the 6%. so whats the formula for shock and raise 1 ppm ?

Would this be the right order to do things in ??

THANX AGAIN !!!

BTW as best I can tell, I am in the 100-120 range on the evapomap.

[chem geek]

Since you have a vinyl pool you don't need to increase your Calcium Hardness (CH). It's good that you have a vinyl pool because the relatively high CH of your fill water of 150 ppm (from your earlier post) means that with your high evaporation rate your CH will rise over time rather quickly if your pool is uncovered (using a pool cover will significantly reduce evaporation). Over a year, you will evaporate several times your pool water volume. I don't know the depth of your pool, but if it's 4 feet, then your CH could increase by about 400 ppm in a year. If this is really true, then you're probably going to have to do significant dilution on an ongoing basis (or partial drain/refill each year) unless you use a pool cover.

The Combined Chlorine measurement is probably monochloramine from the fill water since that is what is typically used these days (is your water from the city or is it well water -- if the latter, then there wouldn't be chlorine in it). So don't worry about that, but do add some chlorine to the water and since you want to add both chlorine and cyanuric acid, the easiest and reasonably priced way to do this is to buy some Dichlor granules/powder since every 10 ppm Free Chlorine (FC) you add with Dichlor also adds 9 ppm Cyanuric Acid (CYA). If your 13x21 pool is 4 feet deep (please confirm the depth or total gallons), then that would be about 8200 gallons. You can use The Pool Calculator for your calculations.

To lower the pH to 7.4, if your pool volume is 8200 gallons and with the numbers you have it would take 17-1/2 fluid ounces of Muriatic Acid (31.45% Hydrochloric Acid). This will also lower the TA to 120. If the TA of your fill water is 130, then this is something else that will rise over time due to evaporation, though won't rise as quickly as the CH. If you find that the pH tends to rise over time too quickly for your taste, then we can lower the TA through the procedure described in this post.

So I suggest you do the following in the order indicated (you do not need to wait between these two though obviously do not mix concentrated chemicals together ever).

1) Add acid to lower the pH. Be sure to add acid very slowly over a return flow with the pump running and after you've added it brush the side and bottom of the pool in that area to mix the water. Acid is the most destructive thing to your vinyl -- even worse than concentrated chlorine -- so you need to be careful. If you want to, you can take a bucket of pool water and add some acid to it, mix, and add this slowly over the return flow so it's more diluted, but that's up to you. If you pour the acid very slowly, you should be fine. If you want to avoid fumes from the acid, you can buy half-strength (about 15%) and use twice as much.

2) Add one cup of Dichlor (dihydrate) granules/powder again slowly over the return. Again, brush to dissolve. In this case, pre-dissolving in a bucket of pool water can be helpful. I've found that some brands of Dichlor don't dissolve that quickly -- if it's more powdered rather than granules, it will dissolve faster. One cup in 8200 gallons will raise the FC to 4 ppm and the CYA to 3.7 ppm. You may need to add the chlorine more than once a day the first day or two until the CYA builds up a little. After that, once a day will probably work. Just keep track of your Dichlor addition and stop after you've added around 30 ppm FC or so (about 7-1/2 cups of Dichlor if your pool is 8200 gallons).

After you've done the above, then you can see how things go with respect to chlorine usage. If it drops a lot due to sunlight, then the CYA level can be increased from 30 ppm to 50 ppm and instead of maintaining 3 ppm FC you will maintain 5 ppm FC instead. But see how things go at 30 ppm CYA first. When you've reached the CYA level you desire, you will switch chlorine sources to using chlorinating liquid or unscented bleach (Clorox Regular or off-brand Ultra -- both should be 6%). Unless you have a pool cover, you will probably need to add chlorine every day or at least every other day. When you add chlorine manually, you want to do so slowly over a return flow with the pump running and then brush the sides and bottom where you added the chlorine (chlorinating liquid and bleach are denser than water until diluted/mixed). If you want to automate this, you can investigate getting The Liquidator talked about in this thread.

If the pH tends to rise too quickly, then the TA can be lowered via the procedure in the post linked to earlier. One thing at a time...you'll want to see how things go and "if it ain't broke, don't fix it".

Richard

[notsoMRWizard]

OK - this mornings readings ...

FC=2

TC=2

CC=0

PH=7.4

TA=130

So since TA stayed and PH dropped should I reapeat Muratic acid and aerate ? Or let PH rise first ? I added another cup of Dichlor as well. How soon after adding the dichlor should i test to determine what th fc is so I can track the cya.

One cup in 8200 gallons will raise the FC to 4 ppm and the CYA to 3.7 ppm. You may need to add the chlorine more than once a day the first day or two until the CYA builds up a little. After that, once a day will probably work. Just keep track of your Dichlor addition and stop after you've added around 30 ppm FC or so (about 7-1/2 cups of Dichlor if your pool is 8200 gallons).

So since this morning my FC was 2 not 4 does that mean the cya is really 1.85, or is the chlorine disappating at a faster rate due to little or no cya being present?

It seems if I wait too long to test th FC level I might be adding more than I need and raising the cya past my goal. Would it be safe to say no matter what the FC reads, once I reach 7 1/2 cups of dichlor, STOP ?

Sorry about all the questions, but its the FEEL FOR IT that I'm really trying to learn here, more than the A-B-C's .. if that makes sence. I know how years of experience can be priceless, I'm just trying to speed up the curve a bit.

a few more details. Yes the pool is covered. Unless we are in it, its covered. Day and night. Solor cover, Home Depot special. Black tarp cover during winter. I also came up with 8200 gals. I tracked my water meter and added roughly 7100 gals in the drain/refill.

I have a 1 HP motor on my filter. What should the daily runtime be? I know with no bottom drain some of the water gets filtered twice, so whats the best for that situation. I have made a custom diverter at the inlet so i can aim the water more toward the side, bottom, or areate. I keep the diverter aimed towards the center bottom when the pool is covered and at the side when not covered for skimming. I have in the past run it between 4-6 hrs a day in the early afternoon.

Thanx again Richard for all your help. When it hits 110 here this summer I will be thanking you evem more.

-Chuck

[chem geek]

Chuck,

So since TA stayed and PH dropped should I reapeat Muratic acid and aerate ? Or let PH rise first ? I added another cup of Dichlor as well. How soon after adding the dichlor should i test to determine what th fc is so I can track the cya.

I wouldn't worry about the higher TA you have right now. The use of Dichlor will be acidic (it's roughly pH neutral upon addition, but the consumption of chlorine is acidic). You can deal with lowering the TA after you've got the CYA level set and your chlorine doesn't get broken down as quickly by the UV rays of the sun. With your use of a pool cover, you may not find a fast rise in pH, but just wait until you get to using unstabilized chlorine (chlorinating liquid or unscented bleach) before deciding if the TA needs to be lowered or by how much.

I wouldn't use the FC measurement as your guide to the amount of CYA you've added unless you are unsure of your pool's water volume. Instead, I'd just keep track of how much quantity of Dichlor you add. The CYA level doesn't have to be perfect -- just get a reasonable idea of what it would be based on what you add. The Taylor K-2006 test kit or the TF100 test kit from tftestkits(dot)com will test the CYA level (the former down to 30 ppm, the latter down to 20 ppm). I wouldn't bother testing the CYA until you know you've added enough to get to about 30 ppm.

So since this morning my FC was 2 not 4 does that mean the cya is really 1.85, or is the chlorine disappating at a faster rate due to little or no cya being present?

I'm pretty sure the chlorine is dissipating at a faster rate due to little CYA in the water. There's probably some CYA in the water already since having no CYA would have the FC level drop in half every 30 minutes or so in direct noontime sun (in the summer) so it's a pretty rapid loss with no CYA. A little CYA will slow this down quite a bit.

It seems if I wait too long to test th FC level I might be adding more than I need and raising the cya past my goal. Would it be safe to say no matter what the FC reads, once I reach 7 1/2 cups of dichlor, STOP ?

Yes. Stop adding Dichlor when you've reached the quantity you indicated. That's the best approach. Once the CYA is at 30 ppm, you'll want to maintain a target FC of around 3 ppm and definitely don't let the FC drop below a minimum of 2.2 ppm so if it's necessary to start at 4 ppm to end up above the minimum the next day (or whenever you next add chlorine), then that's what will need to be done. I suspect your FC drop will be lower once the CYA level gets up a bit.

Sorry about all the questions, but its the FEEL FOR IT that I'm really trying to learn here, more than the A-B-C's .. if that makes sence. I know how years of experience can be priceless, I'm just trying to speed up the curve a bit.

You are absolutely right that you want to get a "feel" for your pool. Every pool is a little different due to the differing environments, amount of sunlight, amount of aeration and surface area to volume, amount of organic material getting into the pool, differing circulation, etc.

a few more details. Yes the pool is covered. Unless we are in it, its covered. Day and night. Solor cover, Home Depot special. Black tarp cover during winter. I also came up with 8200 gals. I tracked my water meter and added roughly 7100 gals in the drain/refill.

Having your pool covered most of the time helps explain the lower chlorine loss even without any CYA in the pool. That's fine. Even with a covered pool, you still want some CYA in the water since the chlorine loss is far too fast without it. Nevertheless, in your situation, I suspect that 30 ppm CYA will do just fine. That's what I have in my pool and I keep mine covered when not in use, but it's an opaque electric safety cover so probably lets in even less UV than your cover which I presume is a clear "bubble" type. It probably filters some of the UV, but not as much as an opaque cover (but having it be clear helps to heat the water from sun that shines through). The chlorine use in my pool is a little less than 1 ppm FC per day if used most every day. If not used every day, then the FC drops around 0.5 ppm per day.

I have a 1 HP motor on my filter. What should the daily runtime be? I know with no bottom drain some of the water gets filtered twice, so whats the best for that situation. I have made a custom diverter at the inlet so i can aim the water more toward the side, bottom, or areate. I keep the diverter aimed towards the center bottom when the pool is covered and at the side when not covered for skimming. I have in the past run it between 4-6 hrs a day in the early afternoon.

You are absolutely right that one of the worst things about most above-ground pools is their lack of a floor drain. That tends to cause a "dead space" at the bottom of the pool. Your custom diverter sounds excellent. If you aim the diverter down and a little to the side instead of directly to the center bottom, then you should create a bit of a swirling effect with the water which should circulate well even in the center. What you have isn't bad -- I'm just thinking of adding a bit of rotation to the water to help with circulation.

As for pump run time, that depends on the GPM flow rate in your system. How many returns are there in your pool? I suspect there is just one and one skimmer, right? If so, I'm surprised at having a 1 HP pump for your smaller pool volume. Do you know if the pipe from your pump to the return is 1.5" or 2"? Do you have a pressure gauge on your filter and if so, what does it read when the pump is running? Do you know the gallon-per-hour (GPH) rating of your pump? Let's say that it's 40 GPM (2400 GPH). That's around 3-1/2 hours per turnover. Frankly, I'd be surprised if you are getting that kind of flow rate out of one return unless it's extra large piped with 2" pipe instead of 1.5". If you give more details about your pool brand and pump brand, perhaps others here can estimate the GPM rate better. With an above-ground pool without the floor drain, you are better off having more than one turnover per day -- two would be reasonable though you could see if you could do 1.5 turnovers as a compromise to keep energy costs down. It really comes down to what is needed to keep your pool clean and clear.

Richard

[johnnys]

I am confused.

If the water situation is so bad like described here, wouldn't it make sense to just drain and refill with clean tap water, rather than to dump so much chemicals in it?

[chem geek]

I am confused.

If the water situation is so bad like described here, wouldn't it make sense to just drain and refill with clean tap water, rather than to dump so much chemicals in it?

That's always an option though with above-ground pools one must be careful as a complete drain can make it collapse or deform. One can use the sheet method for water exchange (draining water underneath the sheet while filling in from above the sheet), but most pool users just clean up their pools by physical removal, some dilution (if certain chemicals such as CYA are high) and lots of chlorine and filtering/backwashing. There's more than one way to attack a problem. In this particular case, a nearly complete drain and refill was actually done, as noted in this post in this current thread. Some of the initial problems were due to the heavy addition of copper algaecide -- copper kills algae, but it doesn't go away and can lead to staining, green water, and greenish hair (for blonds) at higher pH or higher copper levels.

Richard

[notsoMRWizard]

I honestly think the biggest factor was the TDS. It was five years of original water, and never more than a evaporation refill. I think the TDS was at a max. therefore even large amount of chemicals wouldn't work.

Since the 98% refill I've been crystal clear. No more Chlorine tabs. No PH up or down. Ive have , to this point, only added 8 lbs of dichlor (approx 1/2 lb every other week or so) to bring the CYA up to 30, barely. My PH is up or down .2 to .4 every third day or so, but just aerating water(return water pumped into the air over the surface) brings ph up in a matter of a few hours.

I am shooting for a CYA of 40, due to the evap in my area, the solar cover speeding up algea growth, and hopefully to help the liquid chlorine last just that much longer, as that will be my chlorine of choice once the CYA is where I want it.

We don't use the pool during the week yet, just weekends so far. This is the least amount of work I have ever had to do to keep crystal clear. I don't even look at the pool untill Friday in the am, I add the dichlor. Saturday morning I aerate, and by 10 or 11 all levels are perfect.

Thanx for all advise. I agree a refill is a smart choice in a case like mine. I also know now I need to do a partial refill each year just to keep the TDS from maxing out.

[chem geek]

The problem was the high level of Cyanuric Acid (CYA) which you reported was at least 110 ppm. CYA makes chlorine less effective since it binds to chlorine so you need a much higher Free Chlorine (FC) to be able to kill algae. That was the problem, not the TDS. TDS is mostly salt and is much higher in saltwater chlorine generator (SWG) pools at > 3000 ppm and yet is not a problem (for algae growth or chlorine consumption). It's not the 5 years of old water in your pool that is a problem either -- unless you count the fact that CYA was building up over that time. Again, it's the CYA that is the problem. Unfortunately, since the only way to lower the CYA is to do a partial drain/refill, then that was a reasonable option for your pool. You didn't have to do a full refill, but it doesn't hurt (except for some extra chemical costs).

The copper algaecide helped one problem and created another, but the original problem was letting the CYA get too high by continued use of Trichlor. This is a very common problem.

Richard