High CYA and chlorine consumption

[sjmiller]

I sure wish I had found the Pool Solutions web site in 1997 when I bought a house with a pool (10K gal vinyl)! I have been at the mercy of the pool store associates - and have the cabinet full of pool chemicals to prove it. I've been fighting a never ending battle with algae for the last few years. I'm migrating to the BBB method of maintaining my pool.

My current readings are:
Total & Free available chlorine is 5 ppm
CH 220
TA 120 (down from 190 using muriatic acid & aeriation)
PH 7.6
TDS 900

So far I have changed out about 30% of my pool water and CYA is still reading 100+. I'll continue to do 10% a day until I get CYA under 100. Using the Pool Calculator, I'm adding 80 oz of 8.25% chlorine every day to get my chlorine up to 6ppm. When I check the chlorine level the following day it is down to 2 ppm.

Is 6ppm chlorine a good target for now, and will my chlorine consumption level out after I get CYA under 100?

[PoolDoc]

I registered PoolSolutions.com in 1996 . . . where were you?

Anyhow:

1. Read the Best Guess chart page, linked in my blue signature block. It answers the questions you are asking.

2. Get a K2006 testkit; it's nearly impossible to manage a high CYA pool without one.

3. Changing 10% of water at a time is VERY inefficient. If you can do so safely, changing 1/3 or more at a time is much more effective. Of course, if you have a vinyl or FG pool, it's not safe to drain.

4. When you get the K2006, test by mixing 1 cup of pool water with 1 cup of tap water, and then testing the mix. Multiply your CYA test result x2

5. You CAN operate a high CYA pool, simply by using high chlorine levels. There are actually many advantages to doing it this way.

6. Since your pH, TA, & CH are OK, it's OK to ignore pH readings for awhile. 5 ppm FC will NOT kill algae when you have 100+ ppm CYA. Buy a cheap OTO test kit (yellow drops). Add PLAIN 8.25% bleach, 3 gallons at a time, till you reach the DARK yellow / ORANGE-ish yellow OTO level (FC > 15 ppm). Don't go higher till you have the K2006. But, at this level, you should begin to at least control the algae.

[sjmiller]

I registered PoolSolutions.com in 1996 . . . where were you?

I'm here now

Anyhow:

1. Read the Best Guess chart page, linked in my blue signature block. It answers the questions you are asking.

I have been going through the blogs & Tips and figured out that the "guidance" I was receiving from the pool store was WRONG. The latest test they performed resulted in a recommendation of using "brand name" Chlorine Neutralizer to lower my chlorine to 2.0 - 4.0 even though I have a CYA 100 or above. It's now obvious to me why I've been having a persistent algae problem.

I have the k2006 kit on order.

One of the things I find that is very cool is the Tips & Tricks on how to use the test kits. I think it's one of CarlD's tips to use 1/2 pool water & 1/2 distilled water so I can estimate my chlorine levels above the 5 ppm my DPD kit can do. Your recommendation to do basically the same to get a better idea of my real CYA level - something I would have never thought about.

A big thanks to you, and the other moderators & contributors! I now have a much better understanding of pool chemistry and look forward to not fighting my pool - but enjoying it.

[PoolDoc]

You're welcome.

[sjmiller]

My water is clear and I’m no longer seeing signs of algae. My K-2006 kit arrived and my initial test results were:
FC 12.5
CC 0 (1)
pH 7.6
TA 130
CH 200 (2)
CYA 130 (3)
To get my CYA down I drained another 30% of the pool water, and added bleach in the afternoon to bring up the FC. With a CYA 60, my target FC is 7 ppm.
7:00 pm 10:00 am 7:00 pm
FC 7 5.5 (added 22 oz bleach) 3 (added 60 oz bleach)
CC(1) 0 0 0
pH 7.6 7.8 (added 6 oz muriatic acid) 7.6
TA 110 110 110
CH(2) 110 110 (add 32 oz Calcium Chloride) 120 (add 16 oz Calcium Chloride)
CYA 60

(1) When I add the 5 drops of R-0003, the water gets a very slight pinkish hue – not the deep pink I get when I initially add the R-0870 powder.
(2) When I added the R-0011L liquid, the sample turned red, a red sediment also formed and was suspended in the test sample. Is this normal and that I only care about the solution turning blue?
(3) I used 1 cup tap water mixed with 1 cup pool water for the test, results X 2

It seems like I’m adding a lot of bleach or does this sound about right?

[PoolDoc]

Your test results are fine. Regarding your testing notes: (a) most pools have at least a slight reaction to R0003; it's not a problem. If your CC was completely 0.0, you'd have no reaction or color; (b) red particles are OK; (c) 50:50 mix = 2x results, which is what you did, so you're fine.

If this: http://www.intexcorp.com/index.php/h...s/54979eg.html
is your pool, you have about 8,400 gallons of water, for a PF of 14. 22oz is about 20% of a gallon. So adding 22 oz to your pool:
0.20 gal x 0.7 lbs Cl / gal x 14 (PF) = 2 ppm chlorine -- an acceptable small dose. 60 oz would be about 5 ppm.

Typically, there will be some continuing chlorine demand while you clean up algae and its residues. Since you used algaecide, there may be even more.

Once things settle out, you may see a daily chlorine consumption of 1.2 - 2.0 ppm / day. That's about 1/4 gallon of bleach per day. But, this may take a week or more with no trace of algae.