Why does it take so much MA to keep PH under control?

[serge]

Just curious to know if anybody else with a SWCG has to go through 1.5 gallons of MA a month to keep PH at 7.6-7.8 range...my numbers are consistently as follows:

TC=3.0-4.0 range
FC=3.0-4.0 ranhe
TA=70-80 range
PH=7.6-7.8 range
CYA=50 (jusr recently increased from 30)
CH=500
Borates=30-35 range

I'm running my pump 4 hours a day (will increase to 6 as we reach 80º-85º water temp) and set the SWCG at 25%

Any comments appreciated..

 

[JohnT]

Constantly rising pH is a side effect of the SWCG. If you raise your CYA, you'll need less run time which will reduce the pH rise.

How old is your plaster?

 

[serge]

Thanks JohnT...the plaster is 9 months..I suppose as it finally cures, balancing should be easier...not that it's a problem now, just that it seems like a whole lot of MA...

 

[JohnT]

Yeah, new plaster plus SWCG equals a lot of MA.

 

[JasonLion]

A fair bit of that PH increase is from the plaster curing. You can reduce the PH increase from the SWG by raising CYA to 80, lowering the percentage till your FC level is correct again, and allowing TA to go down to 60.

 

[serge]

ok, but increasing CYA won't imply having to increase chlorine output to counter CYA/Chlorine bonding, thus having to run the SWCG at higher rates, thus raising PH again?...tricky, isn't it?

 

[Bama Rambler]

It's kinda strange how it works. Increasing CYA reduces the amount of FC that gets burned off by the sun thereby reducing the amount of FC you have to replace which means less FC the SWCG has to produce to keep the FC at the proper level so the less runtime means less outgassing and the less it drives the pH up. Whew! That was a mouthful!

 

[JohnT]

ok, but increasing CYA won't imply having to increase chlorine output to counter CYA/Chlorine bonding, thus having to run the SWCG at higher rates, thus raising PH again?...tricky, isn't it?

That relationship doesn't hold for SWCG pools. Check out the Chlorine CYA Chart and note the difference between SWCG and non-SWCG pool levels.

 

[serge]

Woao...I'll just keep my MA routine for now, until plaster cures. Then I will try to reach a new equilibrium...thank you all for your comments

 

[lovingHDTV]

I use about 2 gallons of MA per month to keep my PH/TA in check.

In central TX we have very high TA so all my fill water is constantly adding TA to the pool that then makes the PH swing worse, so more MA to counter the increased TA from fill water and the cycle continues.

So I average 2 gallons per month.

 

[jcourt]

I spent the first two months with our new pool adding acid manually. After lots of research on this site, last weekend I installed a CAT-1000 PH system and Stenner Pump/Tank combo.

Now we're cruising along at 7.5 with a lot less stress about PH swings in between testing.

 

[serge]

That sounds like a good idea Jcourt...what was the cost(if you don't mind my asking)?

 

[crabboy]

I used a lot of MA the first year and still quite a bit the second year. I keep my TA low, at about 60-70 and my PH stays fairly stable now. Once we start using the slide it will start creeping again.

 

[jcourt]

Serge - all in about $1,300 if you install it yourself.