Pool consumes 1 gal acid, 1 gal bleach per week?

[jamescookmd]

I refilled my pool 5 weeks ago due to high CYA and started TFPC. I'm having trouble with my pH creeping up, and my FC drops faster than I had hoped.

This week was typical:
Last Saturday: pH 7.8, FC 2, TA 90, CYA 50, CH 230 -> added 1 gal muriatic acid, 1 gal 10% bleach
Next day: pH 7.4, FC 6.5 -> looks good
Today, 6 days later: pH 7.8, FC 2 -> ack!

This is typical, my pH creeps up ~0.4 units per week and FC drops by 4-5. :-(

My pool is 2/3 covered with floating sheets (it's a weird shape). Water temp is ~75 deg. I don't have any water features or anything that would aerate the pool. I'm starting to get light algae blooms, probably because my FC dips low at the end of the week.

I'm spending $10 per week on pool chemicals. Is there anything I can do to keep it balanced for longer? Why does my pH creep up?

Thank you,

James

 

[mknauss]

You might want to review this Pool School - Basic Pool Care Schedule

You should be adding chlorine EVERY DAY. Keep the FC in the target level [FC/CYA][/FC/CYA].

If you have algae, you most likely need to SLAM Process.

pH rise is fairly normal. When using liquid chlorine you are no longer adding acid via the trichlor pucks. If you let the pH rise to 8 prior to adding acid to drop it to 7.6, you may find you use less acid.

 

[DeanP66]

james,

1 gallon of liquid chlorine is nothing. I test FC every day and usually lose between 1.5 to 3 PPM per day with CYA at 50 like you. We have similar size pools. I gallon of 10% liquid chlorine gets us barely over 5 PPM FC increase. So, even at a 2 PPM loss of FC per day, a gallon will only last a couple of days. Also, when the weather warms up soon, it will be using even more.

With your CYA at 50, you should be dosing your FC to 8 PPM and never letting it get below 4. You surely have let algae start because of the low FC (2). You need to perform a quick SLAM to clear everything up. Dose FC to 20 and keep it there until you pass the 3 criteria. Then you can let FC fall to regular levels. Remember, never let it get below 4. That's the golden rule.

Regarding your pH rise, remember that you're not using tablets anymore. Those are acidic and help keep the pH from climbing. Without them, it will climb some. One way to slow that down is to lower your TA some. Bring it down to 60-70 with muriatic acid and aeration and it will help the pH from climbing so fast. I generally add some muriatic acid every couple of weeks to bring mine down from 7.6-7.8 to around 7.2. I had metal staining in my pool and it's best to run your pH on the lower end (7.2-7.4) to help keep the stains from coming back. If staining is not an issue for you, you can run it a little higher. 7.4 - 7.8 is fine. Once it hits 8.0, dose it down to 7.4 with muriatic acid. That should give you a little more time between doses.

 

[Quant]

In my 31k Gal pool I am going through a gallon of 10% bleach every other day. Though down here in Arizona we get more sun than you, but not that much. You need to test more often and put even more chlorine in. Probably close to 3 gallons of 10% a week.

I also had hoped that trouble free pool would be something like the days when I would load up the float will tablets weekly and forget about it. But TFP actually means more time spent on maintenance and the "Trouble Free" part is not getting algae, sick from your pool, or having other problems. It is not much time--maybe 10min but it is every other day instead of just once a week. I will eventually figure out a way to streamline it Here is what I am shooting for:


Sun: Test Water and adjust PH & Chlorine
Mon:
Tues: Throw some Chorine in because I know it needs it.
Wed:
Thurs: Test Water and Adjust PH and Chlorine
Fri:
Sat: Throw some Chorine in because I know it needs it.
ect....
Perform other water tests monthly (TA, CYA, CA, ect..)

Apart from setting up a metered pump to push liquid chlorine with automation, I don't see TFP being any less than fiddling than this. I can't go back to tablets because that just leads to an unsanitary pool and if I paid someone I would just get an unsanitary pool with expensive algae suppression. And Algae is not even a health risk but suppressing algae gives the appearance of a sanitary pool.

Welcome to real world of water chemistry.

 

[mknauss]

Until you are very familiar with your pool, you should be testing daily.

Two options for less time are a SWCG (buying the chlorine up front) or installing a Stenner pump system to add the LC.

 

[jamescookmd]

OK, sounds like I need to be testing much more often and adding more chlorine.

Just curious, where does the acid go? Even when I was using tablets I was seeing a pH rise of 0.2 to 0.3 per week.

 

[mknauss]

You should pour the muriatic acid in a pencil size stream at the return flow with the pump running. If you wish, you can run your brush around the area after adding. Use eye protection and try to be upwind as there are fumes.

 

[jamescookmd]

Sorry, I meant, when the pH rises, the pool is either losing acid or gaining base. I'm not adding significant base (the pH rises even when I don't add anything to the pool). So where does the acid go?

 

[mknauss]

pH rises due to aeration (from CO2 out gassing) or the addition of higher pH water. When you add the acid, it consumes alkalinity and then the cycle repeats.

The pool does not 'lose' acid.

 

[DeanP66]

That's why we say that dropping your TA some can help reduce the pH rise, and even when it does rise, it requires less and less muriatic acid do drop it again. If the TA is really high, you have to add more and more acid to get that same pH drop.

 

[jamescookmd]

Ah, CO2 outgassing. That makes sense.

Thanks everyone for the advice!

 

[aggiejet]

pH rises due to aeration (from CO2 out gassing) or the addition of higher pH water. When you add the acid, it consumes alkalinity and then the cycle repeats.

So I’ll jump in here with a similar question.

I’m adding about 15-20 oz of acid about every day, Even when no one is using the pool. So should I be concerned that my Ph is rising that much every day (about .2) trying to keep it at 7.4, (TA 90) per the pool math guidelines and that I’m adding acid everyday?

I bought some dry acid yesterday because when I’m gone, my spouse doesn’t like handling muriatic acid. Any comments or thoughts regarding use of dry acid?

 

[kairus00]

In my 31k Gal pool I am going through a gallon of 10% bleach every other day. Though down here in Arizona we get more sun than you, but not that much. You need to test more often and put even more chlorine in. Probably close to 3 gallons of 10% a week.

I also had hoped that trouble free pool would be something like the days when I would load up the float will tablets weekly and forget about it. But TFP actually means more time spent on maintenance and the "Trouble Free" part is not getting algae, sick from your pool, or having other problems. It is not much time--maybe 10min but it is every other day instead of just once a week. I will eventually figure out a way to streamline it Here is what I am shooting for:


Sun: Test Water and adjust PH & Chlorine
Mon:
Tues: Throw some Chorine in because I know it needs it.
Wed:
Thurs: Test Water and Adjust PH and Chlorine
Fri:
Sat: Throw some Chorine in because I know it needs it.
ect....
Perform other water tests monthly (TA, CYA, CA, ect..)

Apart from setting up a metered pump to push liquid chlorine with automation, I don't see TFP being any less than fiddling than this. I can't go back to tablets because that just leads to an unsanitary pool and if I paid someone I would just get an unsanitary pool with expensive algae suppression. And Algae is not even a health risk but suppressing algae gives the appearance of a sanitary pool.

Welcome to real world of water chemistry.

Probably worthwhile to invest in a SWCG. I test FC weekly and I'm always 4-6ppm. I've also put borates into my pool and find I don't have to add muriatic acid as often.

 

[mknauss]

pH rises due to aeration (from CO2 out gassing) or the addition of higher pH water. When you add the acid, it consumes alkalinity and then the cycle repeats.

So I’ll jump in here with a similar question.

I’m adding about 15-20 oz of acid about every day, Even when no one is using the pool. So should I be concerned that my Ph is rising that much every day (about .2) trying to keep it at 7.4, (TA 90) per the pool math guidelines and that I’m adding acid everyday?

I bought some dry acid yesterday because when I’m gone, my spouse doesn’t like handling muriatic acid. Any comments or thoughts regarding use of dry acid?

Unless you have issues with calcium scale, allow your pH to rise to 7.8 or even 8 prior to dropping it back to 7.5 or so. See if you use less acid that way. If you wish more discussion about this, please start your own thread.