Advice needed high CYA, new to forum.

[MarkOldham]

We have had this house and pool a little over three years. When we got it, the previous owners were using Home Depot puck and granulated chlorine. Not knowing better, I continued to use the exact same stuff. Sometimes I would also dump liquid chlorine (from home Depot) in trying to get the chlorine level to stay up (it did not work).

3in tablets (trichloro-s-triazinetrione 99%) in a Rainbow Lifegard in line automatic feeder (after filter and heater). (over 70lbs in three years).

Quick disolving chlorinating granules sanitizer and shock (Sodium dichloro-s-triazinetrione dihydrate 99%) scattered in pool. (over 400lbs in three years)

I started looking around online after fighting with green algee non stop for the last year. It seems no matter how much chlorine I dump in the pool, it is gone within 24 hours and it won't keep the algee down. I have put 4 quarts of Algicide 50% (see below) in the pool in the last three years, and there was an empty bottle of it here when we purchased the house, so I suspect at least 5 quarts have been put in the pool, possibly more. I can't keep the algee away for more than three days during the summer, more than ten days in the winter.

After trying to lower the TA as detected by my 5 way home depot test kit for the last month using the lower ph, areate pool, repeat method, (successfully lowered from 350 to 240 as measured by that test kit then stalled and would not lower any more) I purchased the TF-100 test kit. I ran the CH test two times to make sure I didn't make a mistake and got 1300 both times. I ran the CYA test once with straight pool water and the liquid didn't even make it 1/4 the way from the bottom of the sight tube to the 100 mark before I couldn't see the dot, so I diluted the pool water with 3 parts distilled water and ran the test again, it made it about 2/3 of the way up the sight tube from the bottom to the 100 mark before it was impossible to see the dot. By measuring the tube on both readings and calculating, I am guessing my CYA is just over 600, I am sure it is well over 400. Using OTO to test, I got my chlorine to 3.0 using bottle bleach at dark last night, this morning an hour after sunrise, it was zero.

Pool Water:
pH = 6.8
FC = 0
TC = 0
TA = 220
CH = 1300
CYA = 400+
Temp = 74

At least 5 quarts of Pool Time Algicide 50% since last fill
((n-alkyl (C14, 60%; C16, 30%; C12, 5%; C18, 5%) dimethyl benzyl ammonium chloride 49.8%; n-dialkyl (C14, 60%; C16, 30%; C12,5%; C18, 5%) methyl benzyl ammonium chloride 0.2%))

Fill water:
TA = 200
CH = 210

My question is: Is there any way to resolve the chemical problems I seem to be in without draining at least 90% of the water out of the pool? And, until I can drain and fill the pool (might be a few months), what chlorine level do I need to reach to shock the pool, and what level should I be keeping the chlorine at?

Take care,

 

[duraleigh]

Hi, Mark,

Welcome to the forum.

You have a mess, as you know. I am going to suggest you start to replace water immediately and continue to replace it in increments until you can get about an 80% or so replacement.....That should be CYA somewhere areound 40-50 and CH less than 300.

Trying to salvage your existing conditions for the remainder of the pool season will cause you more chlorine than it's worth.

Tell us how your water looks currently and it'll hel[p determine a suggested route to follow.

 

[MarkOldham]

Water is clear currently, but green algee keeps growing on the walls and steps. I brush it off, dump a bunch of chlorine in the pool, but the algee is back 1-3 days later (it always shows up overnight). There are drought restrictions on water use right now, and the city probably won't give me a permit to drain water out of the pool right now because of it, so I am probably stuck with this for another month or two. Should I give up and let the pool turn green, or is there an amount of chlorine I can put in and keep up, or should I just keep brushing and dumping in a couple gallons until I can drain?

Take care,

 

[duraleigh]

I doubt a gallon daily would have little effect on your situation. As I said, I think I would simply give up trying to save the pool until you can get CYA and CH to a manageable level.

You can add chlorine daily and it might hold algae at bay but I doubt even a daily addition will clear it completely.....it needs to be replaced.

 

[zea3]

Welcome to TFP! I wish I had better news for you but the only way to get rid of excess CYA and CH is to drain and replace water. Since you have an inground pool I would not drain more than 1/3 of the water at a time. I plugged your numbers into the pool calculator and it would take phenomenal amounts of liquid chlorine to clear up algae in your current situation. With a CYA of 400 your daily maintenance level would be 30-43 and your shock level would be 75ppm. That would be 45 96 ounce jugs of 6% unscented household bleach just to raise the water to shock level plus you would need to keep the water at 75ppm until all the algae was killed which usually takes at least a couple of days of adding bleach every couple of hours. I do not say this to discourage you, only to point out how important it is to replace your water.
Even if you don't go after the algae until spring, you should not let the pool sit with CH that high and pH that low. Even if you can only drain and replace a few inches of water a week, that is better than the mess you have now.

 

[polyvue]

My question is: Is there any way to resolve the chemical problems I seem to be in without draining at least 90% of the water out of the pool?

No, there isn't.

So sorry to join my fellow colleagues in this assessment but everything duraleigh and zea3 have written I must agree with. However, in Burbank, you probably don't have water table issues, so if you wanted you could probably drain 100% (don't forget to refill, though!)

And that's what I would do. You have a world of trouble in that pool -- and who wants to look at green algae all winter? Declare victory, then withdraw the troops (drain & fill). Good luck to you.

 

[dmanb2b]

Welcome to TFP...your CYA is more likeley somewhere around 240-320 (assuming 2/3 way up is somewhere around 60-80x4(1part pool water..3distilled).

Either way, unfortunately you already got great advice, but i sound like you need to shock and with CYA that high, it would just take a tremendous amount of CL to get to shock level.

To shock at a CYA of 300, you would have to raise your FC to about 60 and keep it there until the algae clears...then you would have to maintain a non-shock FC level of around 25ppm according to the pool calc.

in your size pool...to raise FC to 60 it would take about 15gal of 12.5% liquid chlorine (about $45) and then count on using a 5gal container a week, if you want to maintain the higher FC levels.

Honestly, I can't recommend this approach, but hopefully some others can chime in regarding my fear of such high FC levels, but if you can afford the cost of that much chlorine, it may be your only option. Hopefully Jason or Chemgeek can confirm my thoughts.

 

[chem geek]

Drain and refill (even if done as partial multiple drain/refill) is the right answer here. The only other alternative would be an algicide, at extra cost, that wasn't affected by the CYA. PolyQuat 60 would be one alternative, but you've already seen how using a linear quat is only partially keeping the algae at bay. A dose of a bromine treatment (sodium bromide plus chlorine) would be another, but don't overdue it and it would just be a stopgap measure.

I'm sure you realize by now that the CYA went through the roof due to the continued use of stabilized chlorine products, namely Trichlor pucks/tabs in the automatic feeder and Dichlor chlorinating granules. For every 10 ppm Free Chlorine (FC) added by Trichlor, it also increased CYA by 6 ppm. For every 10 ppm FC added by Dichlor, it also increased CYA by 9 ppm. The Calcium Hardness (CH) may be high from the previous owner using Cal-Hypo since for every 10 ppm FC added by Cal-Hypo, it also increases CH by 7 ppm. It could also be from evaporation and refill since the CH of the fill water is somewhat high.

 

[MarkOldham]

Welcome to TFP...your CYA is more likeley somewhere around 240-320 (assuming 2/3 way up is somewhere around 60-80x4(1part pool water..3distilled).

It looks like the only option is to drain the pool. I think I will raise the PH back up to normal with Borax to keep from causing damage to the heater core until I can drain it when the water restrictions are dropped here.

The way I came up with 400-600 CYA was by figuring that half way up the tube from the bottom to 100 would be 200 (the numbers get higher as you go lower in the tube). Diluting to a 3-1 ratio would mean 1/4 of the solution would be pool water so I would have to multiply X 4 to get the result. Since the diluted solution only got to 2/3 of the way up to 100, I calculated that to be approx 130 X 4 or somewhere between 400 and 600.

To be 60-80, it would have to be above the 100 line on the tube if I am reading it correctly.

Not that it matters much when the number is over 200, but just for future reference, does it look like I am doing the calculation right or am I missing a concept here. This is my first time trying to use this kit.

Take care,

 

[dmanb2b]

I ran the CYA test once with straight pool water and the liquid didn't even make it 1/4 the way from the bottom of the sight tube to the 100 mark before I couldn't see the dot,

<my apologies...I mis-read your statement...you didn;t mean 1/4 way up the tube, you meant 1/4 from the bottom to the 100 mark Ouch yes your CYA is probably around the 300-400 range then.

I thought when you diluted you made it 2/3 the way up the entire tube...sorry

 

[PaulR]

The way I came up with 400-600 CYA was by figuring that half way up the tube from the bottom to 100 would be 200 (the numbers get higher as you go lower in the tube). Diluting to a 3-1 ratio would mean 1/4 of the solution would be pool water so I would have to multiply X 4 to get the result. Since the diluted solution only got to 2/3 of the way up to 100, I calculated that to be approx 130 X 4 or somewhere between 400 and 600.

The scale is fundamentally logarithmic although I don't know precisely what it is. 400-600 is as good a guess as any but really, it's just a guess.

70lb trichlor in 28,000 gallons is worth about 170ppm CYA. 400lb dichlor is worth 800-900. With a cartridge filter you're not losing any from backwashing, only from splashout; not that much, in other words. If you feel like running the CYA test again, use 9 parts tap water to 1 part pool water and multiply by 10. (Tap water has no CYA so it's okay, you don't have to use distilled.) I'd guess that result as correct to about +/- 200 but it's as close to knowing for real as you'll get at this point.

Water replacement under water restriction rules is no fun. A couple people up here in the Bay Area have posted about using pool water for irrigation, and using the irrigation allotment to refill the pool; that's about the only other thing I can suggest. It will be slow and somewhat painful, until the restrictions are lifted.
--paulr

 

[Casey]

You've gotten excelent advice. Just wanted to say I hope the sky opens up for you and the drought restrictions are lifted so you can start draining/refilling your pool.

So sorry you're in this mess but look at the bright side... it won't ever happen again as long as you follow Pool School and learn how to properly maintain a swimming pool.

Good Luck.