Chlorine Question, Newbie Owner

[pmj]

We have had our brand new spa for 2 weeks. We have an ozonator and a Nature 2 cartridge. All tests via the aquacheck test are within normal limits except for free chlorine.

ph 7.8

alkalinity 80-120

stabilizer 100-150 (higher side of normal)

We have put a tablespoon of Spa-Boss (Dichlor)

in most days after use (just 2 people, daily use so far, and LOVING IT).

2 days ago we added Metal X because of tea staining (we have well water). Since then the chlorine has been reading .5 or less.

Question is: with the ozonator and Nature 2,what level free chlorine should be wanting to maintain? Do these 2 have anything to do with how much chlorine we should be putting in?

Any suggestions appreciated.

[chem geek]

The stabilizer level (Cyanuric Acid or CYA) is way, way too high. The disinfecting and oxidizing power of chlorine is roughly proportional to the ratio of Free Chlorine (FC) to the CYA level so with the high stabilizer (CYA) level you have, the chlorine is much less effective. In a spa, there is a somewhat hard to kill bacteria that causes "hot tub itch" so that in spas using chlorine without other systems (ozonator or Nature 2) you would want no more than 20 ppm CYA and have a minimum of 4 ppm FC.

In theory with the ozonator and with Nature 2, you can use a lower amount of chlorine, but the high stabilizer level is making the chlorine you could have much less effective. You should be aware that for every 1 ppm FC that Dichlor adds to your spa, it also adds 0.9 ppm of stabilizer (CYA). So with your high stabilizer, you should just be adding unscented bleach to get your FC level to around 4 ppm since that would be equivalent to having an FC level of 0.8 ppm or less if you only had the 20 ppm CYA you should have.

The next time you drain and refill your spa, just use Dichlor 4-5 times and then switch to using unscented bleach (until the next time you drain and refill in a few months, then start over with Dichlor 4-5 times, etc.). With a 20 or so ppm CYA (which a test kit can barely test so just go on the basis of using enough Dichlor to add about 20 ppm FC cumulatively, obviously not all at once), then after you switch to bleach you can just keep about 1 ppm FC in your spa (you'll need to start with more, maybe 2 ppm, and see if it ends up at 1 ppm the next time you use the spa and before you add more chlorine) and you should be fine since the ozonator and copper/silver from Nature2 should disinfect and prevent algae. Of course, you have another alternative and that would be to just drop the Nature2 completely since it's expensive and you really don't need it since you've already got an Ozonator and are using chlorine. Up to you.

By the way, as for adding MetalX due to tea staining from your fill water, you should understand that Nature2 does nothing more than add copper and silver to your water -- i.e. metals! So adding MetalX may be incompatible with using Nature2 and perhaps it was the Nature2 that was giving you copper staining in the first place. Copper ions tend to inhibit algae while silver ions tend to kill some bacteria (neither kills viruses or protozoa, but the Ozonator should). In my opinion, Nature2 is an expensive waste, especially since you already have an ozonator and that alone should allow you to use somewhat lower chlorine levels. You have to have some disinfectant in the body of your spa water, but chlorine alone (with some conditioner - CYA) is sufficient.

[pmj]

Ok, I am being educated here, thank you for that.

Soo..the CYA is obviousy too high. Is there a way to get that down now? The dealer origianlly told us to add a tablespoon of the Dichlor each night after use for just the first 2 weeks. Was that too much? Is that what caused the high stabilizer level? Can a high stabilizer cause skin irritation?

This water chemistry is very confusing but I am starting to get it, I think.

Thanks for your opinions!

The stabilizer level (Cyanuric Acid or CYA) is way, way too high. The disinfecting and oxidizing power of chlorine is roughly proportional to the ratio of Free Chlorine (FC) to the CYA level so with the high stabilizer (CYA) level you have, the chlorine is much less effective. In a spa, there is a somewhat hard to kill bacteria that causes "hot tub itch" so that in spas using chlorine without other systems (ozonator or Nature 2) you would want no more than 20 ppm CYA and have a minimum of 4 ppm FC.

In theory with the ozonator and with Nature 2, you can use a lower amount of chlorine, but the high stabilizer level is making the chlorine you could have much less effective. You should be aware that for every 1 ppm FC that Dichlor adds to your spa, it also adds 0.9 ppm of stabilizer (CYA). So with your high stabilizer, you should just be adding unscented bleach to get your FC level to around 4 ppm since that would be equivalent to having an FC level of 0.8 ppm or less if you only had the 20 ppm CYA you should have.

The next time you drain and refill your spa, just use Dichlor 4-5 times and then switch to using unscented bleach (until the next time you drain and refill in a few months, then start over with Dichlor 4-5 times, etc.). With a 20 or so ppm CYA (which a test kit can barely test so just go on the basis of using enough Dichlor to add about 20 ppm FC cumulatively, obviously not all at once), then after you switch to bleach you can just keep about 1 ppm FC in your spa (you'll need to start with more, maybe 2 ppm, and see if it ends up at 1 ppm the next time you use the spa and before you add more chlorine) and you should be fine since the ozonator and copper/silver from Nature2 should disinfect and prevent algae. Of course, you have another alternative and that would be to just drop the Nature2 completely since it's expensive and you really don't need it since you've already got an Ozonator and are using chlorine. Up to you.

By the way, as for adding MetalX due to tea staining from your fill water, you should understand that Nature2 does nothing more than add copper and silver to your water -- i.e. metals! So adding MetalX may be incompatible with using Nature2 and perhaps it was the Nature2 that was giving you copper staining in the first place. Copper ions tend to inhibit algae while silver ions tend to kill some bacteria (neither kills viruses or protozoa, but the Ozonator should). In my opinion, Nature2 is an expensive waste, especially since you already have an ozonator and that alone should allow you to use somewhat lower chlorine levels. You have to have some disinfectant in the body of your spa water, but chlorine alone (with some conditioner - CYA) is sufficient.

[chem geek]

So let me get this straight. You drained and refilled your hot tub and then used Dichlor for only 2 weeks. Then you measured the CYA levels and they were over 100. Is that right? That doesn't make sense unless you were using way too much Dichlor. To get to a CYA level of over 100 you would have had to have added over 100 ppm FC equivalent of chlorine over the two weeks. That's about 7 ppm FC every day. That is possible (especially if you also used Dichlor to "shock" once or twice), but it's more chlorine than you would have needed -- did you check Free Chlorine (FC) levels each time or did you just add some Dichlor? If you just added Dichlor each night, how did you figure out how much to add? How much did you add and how many gallons are in your hot tub?

As for how to lower CYA, it can only be lowered by a partial drain and refill -- you'd have to dilute about 4/5ths of the water in your hot tub to get it down to a reasonable level (assuming it's at about 100 ppm right now).

The next time you do a full drain and refill, just use Dichlor for just a few days, not 2 weeks, and only add enough for about 4 ppm FC each time. If you let me know your hot tub size, I can tell you how much you should probably be adding, but a good chlorine test kit will give you a better idea. A tablespoon of Dichlor in 500 gallons of water would give 4.15 ppm FC and 3.8 ppm CYA so perhaps your spa is smaller than 500 gallons in which case your FC and CYA increases each night were more. If your spa was 300 gallons, then the FC would increase by 6.9 ppm while the CYA would increase by 6.3 ppm which sounds more like what happened. If you added Dichlor for shocking, then that would account for a large increase as well.

Don't worry about taking a while to get used to all of this. It only sounds complicated initially, but once you get the hang of it then it really is quite easy.

[pmj]

Thank you for your continued patience with me. I wish I was a chem geek

OK, our tub is brand new..initial filling was 1/2/07, 350 gal, 2 people usage 99.9% of the time

So the other day we shocked the spa with non chlorine shock. After 2 days of NON use, we tested the water.

Our ph 6.2-6.8

alkalinity 40-80

barely reading chlorine (.5)

and the stabilizer is back down to 30-50

Actually I see that the 30-50 is good ...but what made it come down?

Here is probably a stupid question- should we be dipping our strip directly into the spa or collecting water in a cup and testing the water in the cup? Does it make a difference?? These levels are from collecting in a cup

Ok, so after doing my homework this is what I think we need to do today:

retest water ( not in a cup??)

if the alkalinity is still low, raise that.

How long after adding the product should we retest the water to determine if it is raised to the proper level?

My research tells me that adding this (alkalinity raiser)in itself may raise the PH, correct?

If not, we then need to raise the PH. How long after raising the PH should we then add the Dichlor to raise the chlorine to 3-5ppm?

ok...I am taking a deep breath.

Thank you,

pmj

[chem geek]

I am going to put your comments in a different font and answer your questions below them. Hope this works.

Thank you for your continued patience with me. I wish I was a chem geek

Trust me, it has its disadvantages. I didn't get married until I was 38!

OK, our tub is brand new..initial filling was 1/2/07, 350 gal, 2 people usage 99.9% of the time

So the other day we shocked the spa with non chlorine shock. After 2 days of NON use, we tested the water.

Our ph 6.2-6.8

alkalinity 40-80

barely reading chlorine (.5)

and the stabilizer is back down to 30-50

Actually I see that the 30-50 is good ...but what made it come down?

Non-chlorine shock (potassium monopersulfate, KMPS) is very acidic. However, it should not have dropped your pH that much. 1 ounce weight (which is probably about 1-1/2 tablespoons) would lower the pH by only about 0.1 units. As for the stabilizer, that doesn't make sense at all. I think your next question will help answer these wild variations you are seeing.

You may need to add more chlorine than you are doing. Add double the amount, to about 8 ppm FC, and see if that goes down to about 4 ppm FC the next day. If so, then add 4 ppm FC the next day and thereafter. You want to get your chlorine to a point where you add some one day and it doesn't go below 4 ppm FC the next day.

Here is probably a stupid question- should we be dipping our strip directly into the spa or collecting water in a cup and testing the water in the cup? Does it make a difference?? These levels are from collecting in a cup

It's not a stupid question (there's hardly any such thing). Collecting water in a cup should be fine -- no need to dip test strips directly into a spa. However, it sounds like you are using test strips. These can be very inaccurate (depending on the manufacturer of the test strips), especially for certain tests. I suspect the CYA test readings aren't particularly accurate which is why you saw such a large change. CYA simply doesn't disappear -- there are some anaerobic bacteria that can break it down, but this is usually in pools over a winter (these bacteria are in the ground as well which is why CYA is considered a biodegradable substance). I strongly suggest you invest in a high-quality test kit such as the Taylor K-2006 which has a drop-based FAS-DPD chlorine test, pH, Total Alkalinity (TA), Cyanuric Acid (CYA) and Calcium Hardness (CH). You really can't adjust your water until you know what is really in it. Note that with the non-chlorine shock, that this will get reported as Combined Chlorine (CC) so to eliminate that interference you can also get the Taylor K-1520 reagent that can be used with the chlorine test. Though these kits are a bit expensive up front, they will last quite a while and are absolutely worth it. Remember that some tests are temperature sensitive, such as the CYA test so have your spa water (in your cup) come down to room temperature before starting the test.

Ok, so after doing my homework this is what I think we need to do today:

retest water ( not in a cup??)

if the alkalinity is still low, raise that.

How long after adding the product should we retest the water to determine if it is raised to the proper level?

My research tells me that adding this (alkalinity raiser)in itself may raise the PH, correct?

If not, we then need to raise the PH. How long after raising the PH should we then add the Dichlor to raise the chlorine to 3-5ppm?

I wouldn't be so sure that the alkalinity is too low. The test could be wrong. You should keep your TA on the low side so that you will prevent the pH from rising from the aeration from your spa jets which will force more outgassing of carbon dioxide (that's what alkalinity is -- sodium bicarbonate -- so your spa is intentionally over-carbonated like a lovely tasty beverage!). You actually do not want to increase your alkalinity right now since raising the pH (by adding pH Up) will also have the alkalinity rise. The easiest way to get your pH up is simply to run your spa jets and aerate your water. This will outgas carbon dioxide and make the pH rise with no change in alkalinity. Stop aerating when your pH gets to 6.9 and then add 1 ounce weight (a little more than 2 teaspoons) of sodium carbonate (i.e. washing soda which is in pH Up). This will raise your pH from 6.9 to 7.5 while also increasing your alkalinity from 60 to 80.

However, doing anything before you get an accurate test kit a very approximate at this point.

ok...I am taking a deep breath.

Thank you,

pmj

Your most welcome. You're doing great, so hang in there and come back with more results and questions.

[waterbear]

Chemgeek, as usual, has given you excellent advice! I would like to add a few thoughts and reinforce some of the things he said.

First, ditch the test strips and invest in a good drop based kit. His suggestion of the Taylor K-2006 is an excellent one if you are using dichlor (and is the kit I would suggest also)! You spent literally thousands on your tub. Is about $60 really a lot to spend on a GOOD test kit? You would be surprised at how easy it really makes water balancing and maintinance!

Nature2 and metal removers are NOT compatible. Putting copper and silver into the water (which the Nature2 does, the cartidge contains copper sulfate and silver nitrate--copper and silver are the 'minerals' that are going into your water!) and then deavtivating them with a sequestering agent (the MetalX, or any other metal remover) is a bit counterproductive! I would ditch the Nature 2, especially if you are on well water and have an iron or other metal problem. Their instuction pamphlet incuded in the copyright 2006 boxes (but not the older ones or on their webisite) no longer is a low chlorine system. They no longer advocate a .5 ppm FC level in a spa. In fact, you should NEVER let the FC in your spa drop below 2 ppm with or without a N2 or ozone ( or any other 'mineral', 'chemical free', miracle', etc. type of product) if you want properly sanitized water! (Cryptosporidium and pseudomonas are pretty difficult critters to kill, it has been found out by recent research!) The newer instuctions have you shock to 10 ppm and maintain about a 2-6 ppm Free Chlorine level in the spa. You would do this WITHOUT the Nature2 cartridge if you were using only chlorine! Know what the N2 is really best at? Generating revenue for your dealer every 4 months when you replace the cartridge! (and I sell them at work! Don't recommend them but do sell them.)

Ozone depletes chlorine and chlorine depletes ozone. Ozone plays with bromine much better! It actually helps oxidize the bromide reserve in the water into active sanitizer. The advantage to ozone it that it will kill microbes and oxidize organics so in theory it will lessen your sanitizer demand. (The ozone takes care of the oxidation so your sanitize doesn't have to.) However, ozone has no residual killing power. In fact, in a properly set up system there should be NO detectable ozone in the water of the tub! (Ozone is toxic). Residual santizer is necesary because every person who enters the tub, no matter how clean they are, introduce sweat, urine, and feces into the water. This means organics that need to be oxidzec and microbes that need to be killed quickly!. Back to my first point--ozone depletes chlorine and chloirine depletes ozone. They can work well together but you need to get them ajusted properly so the ozone is doing enough of the oxidizng and having enough chlorine to act as residual sanitizer. This means at least 2 ppm FC at all times!

I know it all sounds complicated but it really ain't rocket science!