CYA and Calcium Super High

[TXNDallas]

Greetings!

I'm hoping someone will have some good ideas for me. I've got a 26k gal IG gunnite/plaster pool with the majority of volume in the "deep end", pool ranges from about 4ft to 8.5ft in depth. I bought the house about 6 years ago and the chemicals were all a mess--the CYA level was so high there was no effective sanitizing. A year after owning I completely drained and acid washed the pool. Unfortunately the kid at the pool store refused to test my water until I added stabilizer to the pool--in hindsight I never should of done that as it apparently collects in the plaster (original since about 1992) and leaches out as I later learned. Anyway long story short, now its about 5 years hence and I've got CYA levels so high I can't test them with my test kit--maybe 175-200+ range (don't know if it's a linear scale on the measurer) calcium hardness is over 1000 and I can't sanitize the pool effectively.

I'm not really sure how to proceed, I'm in Dallas, TX and I don't know what our water table is like, but I'm paranoid about re-draining the pool and possibly causing a disaster. At the same time, I can't shock the pool to 96ppm which is the mustard algae shock value for that level of CYA...nor can I keep the sanitizer high enough to be effective.

Pool guy is coming tomorrow for the annual DE filter maintenance, but they don't do the chem--I do. I'm probably going to tell him not to recharge the filter once he takes it apart and cleans/puts back together in case I've got to do some kind of draining.

Suggestions?

 

[JasonLion]

Welcome to TFP!

There are only two choices, the obvious one is replacing water, the alternative is seeing if reverse osmosis treatments are available in your area.

When replacing water you don't have to drain the pool, though that is more efficient. You can instead add water at the same time you are taking water out. This uses more total water, but eliminates the risk of the pool floating.

 

[TXNDallas]

Jason,

Thank you for the welcome! I've been trolling on and off over the years! RO is a great suggestion, it will save me on my water and sewer bills too. I'm checking out providers in Dallas now.

I forgot to say initially that this pool is sanitized (not so much now!) with tri-chlor. What are your thoughts about not replacing the CYA at all?--obviously not for the long term--but waiting a week or two and seeing if as the temperature increases the leeching from the plaster increases as well? I was thinking (RO or not) of giving that a try.

I will have to read around the forum for TFP-recommended levels again as it's been a while, first focus is to get the hardness and the CYA dramatically reduced. I'm thinking 100-150 level for calcium, which is consistent with our tap water. I'm not sure how the calcium got so out of control, I don't shock that often with Cal-Hypo though I have been recently as the cost of bleach is a killer and the strength of what I buy at the store is questionable. I had previously got my borates up--both for the softening effect, and to inhibit black algae, which this pool has had. I have never been able to find a decent test kit to measure the levels of borates--the strips are worthless. Any suggestions?

Thanks again for the welcome!

 

[JasonLion]

Try not to over think things. Getting CH down into the 200s is good enough and significantly easier. Likewise, managing an outdoor pool with CYA below about 25 gets quite difficult. Similarly, there are better borates tests, but they are dramatically expensive, and not worth the effort. The effect of borates is similar from 30 to 50 ppm, so you really don't need a precise test.