High PH, Low TA

[Dad2handz]

Ok...so I am having a struggle. Finally got my pool clear and am having to constantly add muratic acid to my pool to keep the PH under control. It is a salt water pool but my salt is low at 2600 (need to add salt but store is out until Friday of this week) I did shock the pool yesterday afternoon and tested the water this morning. Here are my results from today:
CL 5-10
PH Over 8.2
TA 50 ppm

How do I get the TA up to acceptable range without making the PH go up more??? I believe the TA has gone up in the last few weeks while I've been trying to keep my PH down between 6.8-7.0 (which I haven't been able to do!!) so the sand algae on the walls would dissolve.

Any advice??

[CarlD]

my guess would be to lower pH to about 7.0, no lower, then add washing soda (Arm&Hammer in the YELLOW box) to raise pH and TA. pH Up! is the same stuff--at 3x the price. Sodium Carbonate/soda ash/washing soda may be your best bets.

[Dad2handz]

Thank you Carl, do I add more muratic acid to lower the PH?? And how much of that can I add before it becomes too much? Seems I have added a gallon a week for the last few weeks!

[Watermom]

Before doing anything, you need to verify that your pH reading is accurate by testing when your chlorine is below 5ppm. When chlorine is higher than that, it can cause falsely high pH readings. (If you are using a Taylor K2006 kit, pH readings are reliable with chlorine levels ups to 15ppm.) If it is indeed high, then do lower it with muriatic acid as Carl stated above but please read the tab in my signature about using muriatic acid safely.

[PoolDoc]

@WaterMom: the Taylor phenol red is good to FC=10. Above that, you can dilute 50:50 with distilled (not tap, spring, 'purified' etc. -- just distilled) water. That will allow accurate pH tests up to FC=20. Distilled water at Walmart => http://pool9.net/distilled/

@CarlD: Using washing soda (Na2CO3) + muriatic acid will certainly work. And, 10 lbs of soda ash will raise the TA about 40% more than 10 lbs of baking soda (NaHCO3). But the downside of that is that you have to buy the 'H' (free proton or acid) that baking soda already has (Na2CO3 vs NaHCO3). I'm pretty sure the economics work out in favor of baking soda, if your purpose is to raise the TA. Certainly, the safety does. Of course, "Dad2" is gonna have to handle MA regardless, because of the pH.

@Dad2handz: Do you have anything that is aerating your pool? A fountain, a bubbler, suction leak bringing air into the pool; an ozonator, or an overflow -- anything like that? Your figures (pH=8+; TA=50) look like those that belong to a pool that's being aerated. Aeration (1) raises pH of pool water and (2) strips alkalinity.

It's common for pools with SWCG's to struggle with a constantly rising pH, but the fact that you've got repeatedly high pH + low TA suggests that something else might be happening.

Bottom line? If you aerate constantly -- or even frequently -- you will have to BOTH add muriatic acid AND baking soda frequently, since you aerated your TA (really, CA or carbonate alkalinity, which is the major component of TA) off into the air as CO2 or carbon dioxide.

Using MA safely => http://pool9.net/ma/

[Dad2handz]

Thank you for the answers! I guess the shock i put in last night was diluted by the sun today. Rechecked when I got home and the readings are now:
CL. .5. (Almost nonexistent!!)
PH 7.4
TA 45ppm

Also no aeration as far as I can tell.

Steve

[PoolDoc]

Next test, test pH, TA, and CH on BOTH pool water and fill water.

[Dad2handz]

Pool Water this morning:
CL. 1
PH. 7.5
ALK 55


Fill water:
CL. 0-0.5
PH. 0ver 8.4
ALK. 140