Consistent Chlorine Problems

[cda]

We still can't get a consistent chlorine reading. When testing, everyday, it shows up clear on our test strips or the dropper type test kit. I am adding about 6 fast dissolving chlorine tablets in our floater every day and it goes up a little bit and then later, nothing there. Can someone explain it? We shocked it last night (which we do once a week) and it went green again for awhile and then woke up to a blue pool.

We treated the pool with PhosFree by Natural Chemistry because the pool store mentioned our level may be high. I purchased a Phosphate test kit and it read high (close to 1000ppb). After following instructions, retested recently and it was showing approx 300ppb. I did read about phosphates and it said that it could cause the chlorine problem. I am not sure if it is working though.

I also noticed that the water has a mildewy smell to it. Sounds funny, but the towels and bathing suits have a mildewy smell.

I hope we can get this figured out before the end of the summer. I feel like a chemist when I go out everyday with all these test kits.

[chem geek]

If your Cyanuric Acid (CYA) level is near zero, then the chlorine will break down in sunlight too quickly. If the CYA level is too high and the Free Chlorine (FC) level isn't raised proportionately, then algae can grow and will consume chlorine. Can you post a full set of numbers from a good test kit such as the Taylor K-2006 or the TF100 from tftestkits.com? If the problem is with algae, then the phosphate remover, if properly applied in the correct dosage, should have taken care of it, though it is not the only way to do so. 300 ppb isn't very high with phosphates -- some people have 2000-3000 ppb and keep away algae using chlorine alone though that does seem to be on the edge.

You said you used shock, but be careful since some shock is Dichlor. You also say you use tabs. Remember the following rules:

For every 10 ppm FC added by Trichlor, it also increases CYA by 6 ppm.

For every 10 ppm FC added by Dichlor, it also increases CYA by 9 ppm.

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

Richard

[cda]

We had a full test run and here are our results:

CYA is 80

FC and Tot Chlorine 0

PH 7.5

Total Alkalinity 144

Metals: None

Phosphates: approx 300-500

The pool is blue and clear. There are no visual signs of algae. We are using slow dissolving tablets in the floater, it has approximately 6-3" tablets in there now.

[cda]

Chemgeek:

We put 6 packets/pounds of Dichlor shock (35% chlorine) in the pool last night and it turned a green color and this morning it is blue with a chlorine reading of 1. On the bottom, however, there is a residue around the bottom of the pool. We are going to vaccuum to waste this morning and continue with our 3" floaters in the skimmer.

After reading alot of posts on this site, I have been seeing that someone has reported having a residue on the bottom of their pools (not your average dirt)and when brushed is a white cloud or dust. Is it algae? Should we treat the pool with a Polyquat 60 algaecide also?

Your help would be appreciative.

Michele

[chem geek]

Do not use Dichlor for shocking the pool. Your CYA level is already high and using Dichlor just makes it higher and that makes the chlorine less effective (needing an even higher FC to kill algae). You should use unstabilized chlorine for shocking, such as chlorinating liquid or 6% unscented bleach. If your Calcium Hardness (CH) is below 250 ppm, you could use Cal-Hypo. The key to shocking a pool is to KEEP the FC level high. If you let it go down, then the algae will start to grow again. See this link for more info on defeating algae and shocking a pool. You keep your FC high, in your case at least at 25 ppm, until you measure <= 1 ppm FC drop overnight, measure <= 0.5 ppm Combined Chlorine (CC) and have a crystal clear pool.

[cda]

Added ALOT of bleach last night and had a high chlorine reading last night after circulation. Early this morning, still high chlorine and the Ph was off the chart....around 11am, after quite a bit of sun, the chlorine was GONE and Ph was down to the normal range. We completely give up. We are wasting money. Don't know what the next step is for us, maybe just a partial drain.

[chem geek]

Normally this situation would indicate that there isn't enough CYA in the water since the chlorine seems to be breaking down only in sunlight. However, you do measure CYA in the water. There is one other report of a similar situation (here) and it's the only other one I've ever heard like this. By the way, the pH will be higher after adding chlorine and the test itself isn't valid at high chlorine levels and will seem that the pH is higher than it really is. After chlorine gets used up, the pH drops back down. So what you are seeing with regard to pH is normal -- what is abnormal is the chlorine going away so quickly.

It is possible to have nascent algae with the water being clear, but usually it will consume chlorine at least somewhat at night as well as during the day (it's more during the day as it grows more during the day). However this doesn't sound like your situation.

I wasn't clear whether you used the PhosFree or not. It's not cheap, but if you have algae of some sort it will stop that growth if you lower the phosphate level. It is something to try, though I suspect it won't work (but would be useful to know not just for you but for the other person with a similar issue).

If the phosphate remover doesn't solve the problem then I agree with you that a drain/refill would be in order. Does anyone out there reading this have any idea what is going on? It's very strange that we've seen this sort of thing twice now. If the problem were ammonia or algae or organics, then chlorine should drop at least some overnight and not just during the day. The problem sounds classically like not having CYA in the water to protect the chlorine.

WAIT A MINUTE! There is one other possibility. Did you by any chance use an algaecide containing Sodium Bromide? It might have a name like "Yellow Out" or something like that as it is typically used to get rid of yellow/mustard algae. This turns the pool into a bromine pool and bromine breaks down in sunlight and is not protected as much by CYA (it does not combine with CYA, though depths are still shielded from the UV in sunlight). The other person did not use sodium bromide so didn't explain his situation, but it might explain yours.

Richard

[cda]

Normally this situation would indicate that there isn't enough CYA in the water since the chlorine seems to be breaking down only in sunlight. However, you do measure CYA in the water. There is one other report of a similar situation (here) and it's the only other one I've ever heard like this. By the way, the pH will be higher after adding chlorine and the test itself isn't valid at high chlorine levels and will seem that the pH is higher than it really is. After chlorine gets used up, the pH drops back down. So what you are seeing with regard to pH is normal -- what is abnormal is the chlorine going away so quickly.

It is possible to have nascent algae with the water being clear, but usually it will consume chlorine at least somewhat at night as well as during the day (it's more during the day as it grows more during the day). However this doesn't sound like your situation.

I wasn't clear whether you used the PhosFree or not. It's not cheap, but if you have algae of some sort it will stop that growth if you lower the phosphate level. It is something to try, though I suspect it won't work (but would be useful to know not just for you but for the other person with a similar issue).

If the phosphate remover doesn't solve the problem then I agree with you that a drain/refill would be in order. Does anyone out there reading this have any idea what is going on? It's very strange that we've seen this sort of thing twice now. If the problem were ammonia or algae or organics, then chlorine should drop at least some overnight and not just during the day. The problem sounds classically like not having CYA in the water to protect the chlorine.

WAIT A MINUTE! There is one other possibility. Did you by any chance use an algaecide containing Sodium Bromide? It might have a name like "Yellow Out" or something like that as it is typically used to get rid of yellow/mustard algae. This turns the pool into a bromine pool and bromine breaks down in sunlight and is not protected as much by CYA (it does not combine with CYA, though depths are still shielded from the UV in sunlight). The other person did not use sodium bromide so didn't explain his situation, but it might explain yours.

Richard

[cda]

I used Phofree from Natural Chemistry approximately 2 weeks ago. Been there, done that...it was expensive as well as all the other stuff we have used.

I also treated the pool 3 days ago with BioGuard® Algae All 60 Algicide 60% Polyquat....expensive for a small bottle.

When testing my CYA, it is in the normal range, approximately in the 30-50 range which is showing ideal on my test kit. After having that tested with the NUMEROUS pool stores in my area, it was always in the normal range. I have kept all the analysis' and it never was out of range. As a matter of fact, the Ph, Alkalinity, Stabilizer were always in the normal range. It was just the FC that was reading 0 at home and at all pool testing stores. I did buy stabilizer just in case we needed it, but never put it in. Do you think I should try it and see what happens? It is probably the only thing we haven't tried.

Also, this sounds funny, but our pool is very blue. We put some pool water in a white plastic bucket and it was very blue, like someone put food coloring in it. Nice to look at, but it has never been that way before and we have had the pool for 8 years.

[chem geek]

Well I'm sorry to say that I'm totally stumped by this one so unless someone else has an idea of what is going on it does sound like some water replacement is the only way out of this.

Just so you know, large doses of PolyQuat will consume chlorine, but normal doses that are recommended won't use that much. In any event, your chlorine loss problem happened before adding the PolyQuat and any loss with PolyQuat would happen at night as well as during the day so that doesn't explain it.

As for trying more stabilizer, rather than adding it to your entire pool why don't you do a bucket test instead -- actually two buckets. Take two buckets of pool water and to one of them add a small amount of stabilizer (I assume this is nearly pure CYA). If you add 1/8th of a teaspoon to 2 gallons of pool water in a bucket, then that raises the CYA by around 75 ppm. It takes time for the CYA to dissolve (if you have a mortar and pestle you can crush it into a finer powder since that will help it dissolve more quickly). Keep the buckets out of the sun until the CYA is fully dissolved in one of the buckets. Next add 1/4th of a teaspoon of 6% unscented bleach to each bucket which will increase the FC by 10 ppm. After mixing, measure the FC in each bucket to make sure it registers. Leave both buckets out in the sun. Then measure the FC in both buckets.

If the FC holds in the bucket with CYA, then that would indicate that the CYA level just wasn't high enough. However, I doubt this will happen since everything you have described indicates that there is CYA in the water and with Trichlor tabs you've been adding more CYA as you go. Nevertheless, it's worth a shot.

The one other thing to try is to superchlorinate the bucket that doesn't have the extra CYA. Adding 1/2 teaspoon of 6% bleach would raise the FC to 120 ppm. You can leave that out in sunlight for the day and see if chlorine registers at the end of the day. If it's all gone, then that's truly bizarre and indicates something causing very rapid breakdown of chlorine in sunlight as if CYA were not present or were somehow rendered ineffective.

I'm sure that the blue color of the water is some sort of clue, but I don't know what it means.

Richard

[chem geek]

I asked waterbear about your situation and he mentioned two things. First is that the phosphate remover can cloud the water and this would make CYA tests read higher than the actual CYA in the water. Second is that having the water turn green when you shocked it and now be bluer probably means you've got copper in the water. That wouldn't explain the chlorine loss, however, but the CYA bucket test will be informative.

Richard

[cda]

We had the water tested for metals (copper and iron)this past Saturday and then prior to that, and none were present. We also treated it for Metals back when we opened the pool, thinking we had metals in the pool, we used Metal Free from Natural Chemistry, Inc. It must have worked because the tests showed nothing present. However, 3 out of the 4 pool stores we visited did not run metal tests; it was hard to find one who did.

When we added the bleach two nights ago it did not turn green...which is a good thing. Now, to get it to keep a FC reading during the day would be the trick.

After much frustration, I decided to forego the bucket test and put 1 container of Bio Stabilizer 1.75Lbs in the pool. It says on the instructions to run for 24 hours and don't backwash for 48 hours. We will see where that leaves us on Friday night.

Thank you for your help and for trying to solve our problem. We have been looking everywhere for an answer, and none. This weekend may be a drain weekend. A question about that, we have an above ground 24' round pool, how much can we drain? I have heard you cannot drain too much because the liner may get messed up. The pool stores have said that we would have to replace the liner if we do a full drain, but they don't say how much we can drain.

Have a Happy Fourth of July weekend!

[chem geek]

You shouldn't drain more than a foot below the skimmer. So you have several options. You can do quite a few partial drain/refill of about a foot at a time. For a 4' deep pool, eight such partial drain/refills would dilute the water by 90% and would take 200% of your pool's water volume.

If you were to do a continuous drain/refill by draining from the bottom of the pool (via a pool cover pump, for example) while filling in at the top, then it would take replacing 230% of your pool's water volume to dilute the water by 90%.

If you want to drain/refill using the minimal amount of water, then you can use the sheet or silage bag methods. The sheet method uses a very large plastic sheet you put over the entire pool (it drapes over the side) and you drain water from under the sheet while filling in on top of the sheet which then sinks as the water gets replaced. When it reaches the bottom, you remove the sheet. This uses around 100% of the water volume for nearly 100% water replacement. The silage bag method is similar but uses large silage bags instead of a sheet -- draining from outside the bags while filling the bags with fresh water. You don't get full dilution because the silage bags usually don't fill the entire pool volume, but you can get as close as you want (assuming you have enough bags and can keep them upright during filling).

You have a great 4th too!

[cda]

We did a partial drain one foot below the skimmer and we are refilling now. Keep our fingers crossed and see what happens when we add chlorine.

We came back from the shore today and the pool was still blue but no chlorine reading, everything else fine. So, it was drain day.

[cda]

Our numbers last night were PH 7.4, FC 5, Total Alk 120, Stabilizer 100.

This morning, we read PH of 7.8 and FC 2.

Just now, at 3:00pm on a cloudy, warm day we did a reading to see if we still had a chlorine reading, and it was 0...nothing. PH was higher than this morning.

So, my question is, we did a partial drain all at one time....what should we be doing now to get a reading? More shock? More chlorine?

[cda]

In the middle of the week we put some algaecide in, approximately one quart, and then after a day or two the residue on the bottom that we had every day was gone (white/gray residue mixed with dirt) and we started getting a chlorine level during the day. We had 3" weekly tablets in the floater and everything has been fine ever since. I guess the partial drain and the algaecide did the trick. I am keeping my fingers crossed and knocking on wood as we speak so I don't jinx it. Thanks for all the help on the forum.