There is a product that reduces CYA.
I dont know anything about it, but I have heard of it.
I think it is pricey. Cheaper to drain, refill depending on water cost.
Has anyone used a CYA reducer?

Don't go more than two feet at a time. Then refill and repeat.

Use regular unscented bleach or some liquid chlorine from a pool store daily to maintain your chlorine level. It doesn't add calcium.

The pH will rise slowly. Use Muriatic acid to lower it.

Bring the chlorine level up to about 5-7 ppm until the CYA level is down to about the 40-50 range.

On average, it takes about 7 years in my area for the original water to be rotated out and replenished. Splash out, evaporation, backwashing, and lowering below the tile line for winter account for the out bound. Rain and refilling bring it back in. This cycle usually keeps the CYA within reasonable limits. YMMV.

It's not just tabs that bring up CYA. Dichlor powder will do it too.

A salt cell wont. It makes liquid chlorine.

Scott

If your using test strips, I wouldn't trust the results on the cya test. A 50ppm rise in one season is very much out of the norm. Have a pool store test it. If you had that high of a water table in the pool the builder probably put in a hydrostatic relief valve. Call and ask. To reduce the cya by half dump half the water.

Gorilla, go to troublefreepools.com and read pool school and other blogs. This is a great place to find out about maintaining your pool chemistry. There is a free pool calculator that you can use that tells you how much chemicals to add to your pool to bring back to your specfications. Hope this helps....

Don't bet on there being a hydrostatic valve. There may just be plugs. I personally don't like using H-valves because they tend to deteriorate over time.

I would bet that if there was water at 3 feet during the construction, a dry well at the deep end is in place and available to have a pump attached. That would allow you to drain the water around the outside of the shell. Then you can safely dump the 1/2 as suggested by renovxpt.

Scott

Thanks for all the feedback. I will try draining no more than 2 feet at a time.

To address some questions:
- I do have a dry well under the pool that I can tap into with a pump... the PB capped it, so I was trying to avoid cutting the cap off, and renting a pump.
- My test kit is made by Taylor, so I was not using strips. My pool gets sun from 8AM-6PM in summer, and even though water was balanced, I had to keep 5-6 PPM chlorine to avoid algae blooms... I guess at that rate, I was dumping a lot of CYA weekly. Pool is 30K gallons, and I was going through about 4-5 3" tabs weekly.

-Gorilla

Scott, I have to strongly disagree about h-valves. If you have ever seen an olympic pool float out of the ground and cause $100k+ in damages because someone replaced the h-valve with a plug, you would change your mind. In the two states we work in its a requirement for all commercial pools regardless of site conditions. I have seen situations where the pool was not constructed in a water table and floated from pumping out the pool and because the water could not perk out fast enough, it floated the pool. The only problem I have seen with h-valves is when they are in the main drain sump and leaves covered the drain resulting in the valve opening from the low pressure generated by the pump. Once opening there is often sand particles preventing the valve from properly closing. Although this is a nuisance, its a lot easier to fix than a floated pool.

Gorilla, that monster word on the chlorine bucket tells you if cyanuric acid is included in the active ingrediants.

Anyone that doesn't put a dry well system in place before building a pool in an area where the water table is high needs them, I agree.

Darn pain in the butt when the seal leaks pool water out. Sometimes they get put in a drain sump and are hidden by the cover. Happens every year at least once.

I prefer to see the dry well system in place when a pool is expected to be drained at some interval. A lot of commercial pools in my area are in the off season. In the Spring, they get repainted (yuk) and refilled.

Pulling the water from the dry well prevents potential pop ups until the hydrostatic plugs can be pulled. Then the dry well can be shut off.

Hydrostatic relief valves seals deteriorate. The rubber gaskets last from 5 to 10 years. The chances of the same tech draining the pool knowing the valves are there and how old they are are pretty slim. The valves can also get crud stuck in them that prevents sealing.

Scott

The added costs of installing a dry well system however can deter them in the planning and bidding phase.

I haven't tried this myself but I have read where someone was able to replace the water without reducing the water level. This was done by placing a sheet of plastic over the top of the pool. Then they filled the pool on top of the plastic and drained the pool water underneath the plastic at the same time and at the same rate. The plastic sheet would sink as the water on top increased while the water level below the plastic would drop. This is probably far from perfect but I would think it would be good enough to replace most of the water.

Also, the chemical that removes CYA is the same one that is used in the test kits, Melamine and it is very expensive.

"Also, the chemical that removes CYA is the same one that is used in the test kits, Melamine and it is very expensive."

Melamine???? Hmmmm....Wasn't that the trace ingredient that was found in some dog food a couple years back that caused so much canine illness and some deaths as well??? If so, I'd be sure I didn't use the CYA reducer in any pool that the family dog uses for an occasional water bowl. Maybe the melamine turns into a harmless chemical when used as a CYA reducer, but I wouldn't chance it with my family pooches.