Cannot control the pH

[flyinbayou]

I have inherited the care of this pool and have not had much luck keeping the pH down. It is approx. 6 year old, 25K plaster pool with an attached spa/hot tub that flows into the pool and sunning deck at 2 points. I have a recently cleaned Jandy SWG and a pentair 520 cartridge filter (and a heater that is only used occasionally). There was trouble with the SWG sensor a month or so ago and the pool balance really got out of whack but we were able to get everything working and in balance. The problem I have is that it takes an awful lot of MA (~32% acid) to keep the pH level in range. The chlorine level is fine, salt concentration %3.4, the filter pressure is 22 psi (It dropped 10psi after I cleaned the cartridges). But this pool seems to eat MA! At least a gal a week. I was warned by the tech that changed my SWG sensor out that I need to stay on top of the chemicals to keep everything harmonious.
We use the water features infrequently (waterfall, bubblers, deck jets), although when filtering, the water flows/falls from the hot tub into the pool.
What am I missing? Or is this just the personality of the pool.
Thanks in advance!

Tom

 

[tim5055]

Welcome to TFP!

Do you have a full set of water analysis to provide? You say tings like "in balance", but to us we want ot see the numbers. What a pool store says is in balance is vastly different from what we have found to be true.

If you have read around here much you have probably seen that not much credence is given to pool store testing. While you would think that a "professional" would be the best, unfortunately in most cases it is quite the opposite. Between employees who blindly trust the word of chemical sales representatives and high school kids working in the pool store for the summer you end up with poor results from their testing. In my case two different pool stores told me my CYA was "fine", around 70 or 80. When I tested myself I found it over 200.

To follow the pool care methods taught here you need to arm yourself with the knowledge and tools necessary to care for your pool.

The knowledge is condensed in the Pool School link at the top of every page. It is a great community here, but we do ask that you read and try to understand the information being taught. Questions are always welcome and folks will try to direct you and teach you the methods.

The tools are not limited to the brushes, vacuum hoses and other stuff you use around the pool, but include the most important item - one of the recommended test kits. You can buy a kit at a pool store, but again the pool store kits generally won't cut it. To effectively practice the TFPC methods, the FAS/DPD chlorine test is essential. All these kits contain that test while very few other kits do. Think of it this way, do you see a doctor blindly prescribing drugs without seeing the patient or having tests run? Here at TFP we are going to ask for photos so we can see the condition of the water and are going to ask for a full set of test results.

 

[chiefwej]

The problem of constant pH rise is common in SWG pools. You also have constant overflow that causes aeration and additional pH rise. Can you control how much water flows back into the spa? If you can reduce the overflow it may help some. Once you get a good test kit and some reliable test results we can look at TA levels, which can also help to stabilize pH levels. There are other factors and other measures we can take, but the lack of solid reliable numbers make it difficult to diagnose and treat.