Pool with high CYA levels

Hello,

I recently purchased my first house which also has my first pool! Right now I am swamped in the learning curve of figuring out water chemistry/ pool filter equipment/ and new home ownership in general. In short, the house was used as a rental property for the last few years and I assume the pool was neglected a little bit. So far I have been using the pool care company that has been working the pool with the pervious owner to keep everything on "autopilot" while I get up to speed. The other week I took a water sample to the local pool store to cross check the pool guys work and was told that my CYA levels are greater than 200ppm and that the best solution is to drain 2/3 of the water out and replace ... but that I should also be careful not to pop the pool out of the ground because of the water table in Florida. I'm a little hesitant, any advise? I just ordered a Taylor k-2006 so I'm sure there will be many more questions to follow.

The pool is an inground gunite pool/spa combo type aprox 9000 gallons.

Thank you all for the help!

-Chris

Do NOT drain, until you are SURE you can do so safely!

Get an approximate actual CYA level by diluting with DISTILLED water and then multiplying the test result by the appropriate factor:

1. Buy DISTILLED water (not spring; bottled, purified, etc but DISTILLED!) from Walmart or some groceries
2. Take a CLEAN 1 cup measure, add 1/4 of pool water and 3/4 cup of DISTILLED, and mix
3. Test the MIX
4. Multiply the test result by FOUR (4x)

Meanwhile, add 2 gallons of PLAIN 8% bleach per 10,000 gallons of pool water. This should produce a chlorine level of 20+.

When your pool store PANICS, don't worry about it. 20 - 50 ppm of chlorine is FINE, when your CYA is greater than 200 ppm!

Maintain high chlorine levels till you get your K2006 and know more.

Thank you for the quick response, I will get on it and post the results back here!

update:

Well I received my K -2006 kit and started trying to figure out how all the tests work. I did exactly as you instructed for the CYA test and got some distilled water from the store and I mixed 3/4 cup distilled and 1/4 cup pool water. The dot was no longer visible half way between the 50 and 60 mark, so 55 x 4 = 220 CYA. I added the 2 gal of plain bleach and as you mentioned the total chlorine came back pretty high.

OK. That's high, but not unmanageable.

Your safest bet is to operate using either bleach (aka liquid chlorine) or unblended calcium hypochlorite (68+% available chlorine).

1. If your pool water is clear, maintain chlorine levels = 5% of your CYA => 11 ppm
2. If you have any TRACE of algae, maintain chlorine levels = 10% => 22 ppm
3. If your pool has significant algae OR if the algae gets worse go to 15% => 33 ppm
4. If your pool is green, 20% => ~50 ppm

In Florida, you may be able to find "liquid chlorine" or bleach at 10 - 12% strength economically. Otherwise use PLAIN 8% concentration Walmart bleach.

Test your calcium and alkalinity levels. If they are low-ish, you can used calcium hypochlorite, if you can find that economically.

I should add, you CAN swim at all those levels . . . safely.

Bleach baths at 50 - 100 ppm chlorine with NO CYA are recommended every day by dermatologists, even for pediatric eczema.

But, swimwear is more sensitive to chlorine than skin, so if you have to take levels above 30 ppm, wear old swimsuits!

Keep in mind, that with CYA = 200+ your EFFECTIVE chlorine levels are far, far lower than the indicated levels.

One more thing: the very high CYA levels will mean you can probably add chlorine as little as 1x per week, instead of daily.