Do I Really Need To Drain My Fiberglass Pool?

[goldee]

I moved into this bank-owned house and the pool was green and algae ridden. I hired someone to clean the pool and it took two months and alot of chemicals. This is the third summer since that initial cleaning. The pool water looks good, but I notice a cloudy appearance when the pool is in high use.

Total disolved solids have always been very high, ranging from 1500 to 3000. CYA has always been high too 80 to 150. The recommended solution (from Leslie Pools) to both of these issues is to drain the pool and replace with fresh water. I understand there can be alot of complications with draining a fiberglass pool, so in May, I drained off only about 18" of water to lower the CYA, but it did not help much. I am now realizing that the sanitizer I am using is increasing CYA, any suggestions on balancing this pool? If draining is the only answer, do you have any suggestions on how to go about draining the pool or how to ensure the company/person I hire has the right qualifications?

In addition to those issues, I also have had hard time lowering TA and keeping Ph up, so I recently tried Borax. So far, not much improvement on the Ph, but I just started.

I have a rectangular Viking fiberglass pool about 10 years old, 10,000 gal.

This year we put a new (pentair) two speed 1hp pump and filter

I have been using Dichlor (Clor-brite),dry acid, soda ash, and more recently borax

FC = 1.5

TA = 140

Ph = 6.8-7.0

cyanuric Acid > 150ppm

Any insight would be much appreciated.

[waterbear]

Any insight would be much appreciated.

Fiberglass pools can usually be safely drained to a level of about foot below the skimmer so you are really going to have to do a series of partial drains and refills to get the CYA down. Your other option is to hire a pool company to brace the pool and drain it but that can be expensive.

Unfortunately, there is no other way to lower CYA besides draining and yours is too high, period.

What kind of filter did you install? If you are using a cartrdige filter then you do NOT want to use any stabilized chlorine in the future either.

Liquid chlorine or beach is a much better choice for you.

As far as TA goes, what is the TA of your fill water. If it is less than your current TA the water replacement will get you started on lowering it. If it is the same or higher then get the CYA down first and then work on loweirng the TA.

To lower the TA drop your pH to 7.0 (this converts bicarbonates in your water to carbon dioxide. You have just lowered your TA somewhat and also lowered your pH.

To bring the pH back up you need to drive off the carbon dioxide. Carbon dioxide in water is basically carbonic acid, think seltzer--it's the same thing.

We want to make the "seltzer" in your pool go flat by driving out the carbon dioxide gas. With a bottle of seltzer we do this by shaking up the bottle. You want to do the same with your pool by aerating the water any way you can. Point the returns to break the water surface, put in a fountain connected to your return, invite 10 kids over for a splash party. The faster you aerate the faster you drive out the carbon dioxide (and the faster the pH rises back up without impacting TA since we are getting rid of carbonic acid, operative word here is acid.

Now this process is repeated again and again until the TA is where you want it... be warned that with a TA as high as yours you will not see much movement at first but if you keep repeating this it will worl

drop the pH to 7.0

aerate the water to bring the pH back up above 7.5

test TA

repeat until TA is at target.