"normal" Salt, Bicarb and Acid consumption with a SWG

[Dan-H]

I'm trying to understand how much salt usage, Acid usage and bicarb usage is "normal" in a salt pool with SWG.

Pool was converted to salt on 7/6, and on 7/24 salt was 3200.

I added a 40 lb bag in August (I didn't log the date) when the salt indicator and the salt test showed it was a little low.

Last week I added a gallon of liquid to raise the CyA and it moved from 50 ppm to 80-90
A day later I added 4 lbs bicarb as the TA was down from 90 to 60.

Last week I tested Chlorine and PH and added a little (cup or pint) every other day keep the PH down.

Yesterday The low salt light was on my IC40. the diagnostics was showing 2400. I didn't have time to test beyond the basics. The quick 5 drop chlorine test showed it was around 3 and PH about 7.8. I added a pint of acid and a 40 lb bag of salt. equip ran for about 8 hours along with the Kleen Machine was running to stir things up.

This morning the low salt was on again, diagnostics showed 2300 PPM. Two hours later it was 2900 ppm.
Here are today's test

FC 2
CC .5
TC 3
PH 7.8 (acid demand 1 drop not quite, 2 drops too much)
TA 70
CH 180 ? may be suspect my 6yo was helping and we lost count...
CyA 70-80
Salt 2600

I added 1/2 gal liquid chlorine to the spa with the spillway running (does a nice mini-shock of the spa)
and 1 1/2 pints liquid acid. I'm concerned that the low salt is causing low chlorine. I'll see what it looks like tomorrow.

Pool temps run up to 88 during the day with the solar cranked and cool to about 80-82 by morning. My autofil was broken earlier this year and I can loose 1/2 inch of water overnight, especially if it is breezy. Pool is shaded early morning and late afternoon

Pool has auto fill.
Tap water:
Chlorine 0.5 ( 5 drop test)
PH 8
TA 30

questions?:

is the low chlorine a normal side effect of low salt?
how much salt usage is normal? is a bag a month normal for a 15K gallon pool like this?
Does adding CyA cause the salt level to drop?
how much TA loss is normal? is 4 lb a month reasonable?
( I think) the PH rise is normal with the SWG? I'm typically use a couple of gallons of muriatic acid a month. Is this reasonable

We lose some water splashed out with the kids, but not excessive.
I'm assuming when water evaporates it leaves the chems behind.
I can see PH rise with the tap water being added but is this much salt consumption normal?

I haven't checked for a leak but that's my concern if this is excessive.

tnx in advance.

 

[chiefwej]

The SWG system consumes NO SALT. The salt level should remain constant, with only very minor loss due to back washing filter or splash-out. I seldom add a bag a salt a year to my 20k salt pool.

Have you done any tests of salt level other than readings on the SWG control panel? If the cell has any calcium buildup it can cause false salt level readings.

Ph rise is common in SWG pools. My pool needs 1-2 quarts of 31% MA per week to keep the Ph down.

 

[JasonLion]

Don't raise the TA above 70. The higher the TA level, the more the PH will drift up. Much of your acid usage is because you are raising the TA too high.

Unless you have had a great deal of rain overflowing the pool (or forcing you to pump out water) or a leak or you backwash very frequently, there shouldn't be any reason to add salt. It is fairly common for SWGs to suddenly start reading lower than actual salt levels either when the cell plates have calcium scaling (take the cell out and look at it, white crusty stuff is calcium and needs to be cleaned out), or when the cell is getting very close to the end of it's lifetime.

 

[Lershac]

Do you have an autofill? I wonder if you dont have a leak thats being masked by the autofill.

 

[Dan-H]

I'll pull the cell tonight and look at it

Thanks for the tip on the TA. I'll leave it where it is.

We've had zero rain. It is dry and warm so we have a bit of evaporation.

I do have an autofill and the loss of salt has me wondering if I had a leak... I'll try a leak test with a bucket and see if the loss is just evaporation.

One last question. does adding Cyanuric acid affect salt or TA? Cya was about 30 and I added a gallon of liquid stabilizer to raise it.

tnx

 

[bobodaclown]

I believe adding CYA will have a no (minimal) effect on salt or TA.

 

[chiefwej]

If both salt and CYA levels are in fact dropping, you may well have a leak.

 

[Dan-H]

A month ago I replaced the float in my autofill and I think it was set too high and I think I have a tile level leak.

Last monday night, I turned off the autofill and lost about 1/2 inch of water overnight, then about 1/4 inch per day for the next 3 days. 1/4 inch is reasonable evap given the pool is warm and the evenings are cool with a breeze.

Last night I refilled the pool with a hose and( oops ) forgot to turn it off and over filled it by over an inch. This morning it had lost 1 1/2 inches and was very close to the level it was after turning off the autofill.

 

[chem geek]

At typical pool pH, every 30 ppm of CYA will increase the TA by about 10 ppm. I'm referring to CYA's contribution to TA. If you add pure CYA, it doesn't change the TA but it does lower the pH -- if you then raise the pH back up then the TA goes up with it and what I quoted would be valid. If you add liquid CYA (sodium cyanurate), this raises the TA upon addition with little change in pH.