ph won't come up

[piratespoint]

I take care of a 46,000 gallon pool at a small resort. For the last four months or so I cannot get the ph to rise to normal levels. I think part of the problem was the alkalinity was quite high, but I have that under control now. Even so, I've dumped about thirty pounds of soda ash/ph up in there and it still will not rise. I've tried two different test kits, same results. I've aerated the water using scuba tanks. I've been draining a few inches off the top every week and refilling.
Our fresh water comes from the ocean and is run through a reverse osmosis plant and is suitable for drinking. I've tested it for ph and alkalinity and both are in the correct parameters.
To my knowlege, the pool has not been drained and refilled for over six years.
I'm running out of ideas. Any advice or helpful hints would be much appreciated. Thanks!

 

[JohnT]

What is the pH now? What is the chlorine level? It can skew the results of the pH test. A full set of test results would be helpful.

 

[jblizzle]

What are you using to chlorinate the water?

Post up a full set of test results and what you used to get them.

With a pool that size, it may take a lot of soda ash to raise the pH if it has gotten very low. Odd how you say the pH is low but the TA is high ... usually the problems are either both are high or both are low.

 

[Richard320]

I'd like to insert the TFP mantra: Can you post a full set of test results?

The pH test can be affected by high FC levels.

Also check that you're using the right pH reagent. I recall reading somewhere here last year about someone who had picked up the wrong reagent.

 

[piratespoint]

Thanks for your interest. I only have a very basic test kit. The TA is currently around 90, the FC has been up and down during my ph tests. I use mostly the tri-chlor pucks which I understand to have a low ph, but also use granular chlorine which I'm told has a high ph.
When I get into work tomorrow I can give you a bit more information. I appreciate your help!

 

[JasonLion]

There are two common forms of granular chlorine, dichlor is the most common and it is quite acidic. Cal-hypo is the other, though it is normally a powder and not granular, and it is essentially PH neutral.

 

[piratespoint]

I just tested the pool with a Basic 5 Test Kit. FC is 2, ph is 7 maybe a bit less, TA is 120.
The chlorine I'm using is tri-chlor, both my pucks and my granular.
Yesterday I added a couple of pounds of soda ash and today I added a few more. The ph seems to have come up a hair in the last 24 hours, but this is the first time it's budged in a few months.
How long does it normally take to see results after adding the soda ash?
Also, I've heard that aerating the water can help with the ph. As I mentioned in my first post I've drained a few scuba tanks in there, but so far they don't seem to have done much good. Should I continue doing this? It certainly can't hurt anything, but perhaps it is a waste of time.
Thanks for you help!

 

[jblizzle]

It is the trichlor that is causing you to have such a low pH ... this is one reason (on top of adding all the un-needed and problematic CYA) that we do not recommend using that product and to stick to liquid chlorine (bleach) if possible.

The effects of the soda ash should be apparent within an hour (assuming the pump is on circulating everything).

 

[dmanb2b]

In a 46k gal pool, a few scuba tanks won't do much to raise PH. A water fountain or creating your own aerator from some PVC pipe would be more efficient. Below is a pic of one I put together a few years ago with advice I had received back when I joined TFP.

 

[piratespoint]

Thanks for the replies, it looks like the tri-chlor is the culprit. In years past the granular that we ordered was the kind that raised the ph and that must have helped balance the levels. I'm in a very remote place, so we only get one, maybe two orders of chemicals per year. I won't get any more soda ash for at least a month, maybe longer. Aside from aerating, is there anything else I can use to raise the ph? Baking soda?
I have two gallons of liquid chlorine left. Maybe I can use a bit of that each day. Anyone know how much of that would be the equivalent of one of the pucks? Two cups possibly?

 

[jblizzle]

Use the bottom of the poolcalculator.com to calculate the effects of different chemicals.

Baking soda will raise the TA more than the pH. Use the poolcalculator.

Posted from my Droid with Tapatalk ... sorry if my response is short