Pumping Muriatic Acid

[ptbrunet]

Hi, I am currently pumping bleach with a Stenner 45M fixed 10 GPD pump with 15 gallon tank. I'd like to add another one to pump MA. Is there anything I need to consider changing in the specs of the pump for MA?

The bleach pump is controlled via my Pentair control panel but I'm out of circuits so will have to use a timer for the MA pump. Any recommendations for a timer? I'd like to be able to control the pump down to the minute.

I understand I'll need to dilute my MA to keep the fumes down. Any recommendations on the dilution ratio? The store I get my MA from has 31.45% MA.

I'm thinking that I'll only fill the tank up to about the 5 gal level so any splashing will stay in the tank.

If I dilute at 4 to 1 I assume I'd pour in 4 gallons of water and then 1 gallon of MA. Will the MA mix or sink to the bottom and then I'd have to use something to stir it with?

Do I have to make sure I am not injecting MA and bleach at the same time? The injectors will be about 2 inches from each other.

 

[Bama Rambler]

Where will the vessel be located, indoors, in a shed, outdoors, under a cover, etc.?
The acid will fume and eat any metal around unless it's well ventilated or diluted a good bit. You can buy half strength but it's about the same cost as full strength.

I don't know that it will matter much how full the tank is as far as fuming goes.

Yes 4 gallons of water and one gallon of acid.

You need to make sure you're not injecting them at the same time.

 

[ptbrunet]

Thanks BR. It's outside. There are walls around it but open on the top and openings on two sides. Will that be enough?

 

[Bama Rambler]

As long as the walls or top isn't metal you won't have a problem. If they are metal, I suggest you inspect them very well and repair any nicks or scratches in the finish and you should be fine.

 

[ptbrunet]

The walls are concrete, about 5' tall. In the equipment area there is some metal: control panel, pool and cleaner pumps, clamp for the DE filter, various fasteners, etc. and also two nearby air conditioners.

 

[Bama Rambler]

As long as those A/C units aren't right against the MA tank, everything should be fine. Diluting it and given the ventilation you have, it won't be an issue.

 

[ptbrunet]

Thanks. This was a helpful conversation. I was going to put my acid tank closer to the AC units, where the bleach tank is now, about 2 feet from the closest AC unit, but I'll leave the bleach tank where it is and put the MA tank on the other side of the bleach tank so the bleach tank is between the MA tank and the AC units. That will move the MA tank about 20" further away. Also I just checked the cap on the Stenner tank and it's actually more air tight than I first thought.

 

[linen]

Out of curiosity, what are you keeping your TA at?

 

[ptbrunet]

My TA is 70. I also have 50ppm borates.

 

[linen]

How much ph rise are you getting/ how often are you having to add acid? I ask since your new plaster is getting older and your ph rise should be slowly decreasing.

 

[ptbrunet]

I add acid about once a week. Now that I have added borates I am experimenting to see how long I can go before adding MA. First I tried adding a gallon of MA but that's a waste because the rise is pretty fast from the low end. Then I added 1/2 gallon, but that's still too much. The next time I will add 32 oz to drop from 7.9 to 7.6.

My goal is to be able to ignore the pool for up to 17 days so I could leave town for a couple of weeks if need be. At this point even with mature plaster I'm suspecting that this won't be possible; but if it is I might hold off on the pump and wait to see how it goes next Summer.

Another goal is to make maintenance easy if I am ever unable to take care of the pool for an extended period of time and as a selling point when I eventually have to sell the house.

By the way, I don't remember adding much if any MA last Winter and the pool was brand new; is that typical?

 

[linen]

Since you have the 50 ppm of borates, you should be able to lower the TA a little more (maybe as far as 50 ppm) and I would guess you may see the ph stabilize some more. However, you may want to take a look at your csi to make sure you are reasonable near the middle (0).

 

[ptbrunet]

The Pool Calculator shows my CSI at .06 in the first box and -0.18 in the second box. Is that close enough?

What is that second CSI box indicating?

 

[linen]

The left most box is where your csi is at (assuming you inputed your pool test results in the left most column). The csi listed to the right is calculated off the "target" column. Your csi is in great shape! Generally you want to stay between +/- 0.6

 

[ptbrunet]

Thanks linen. I'd appreciate any comments from other TFP members on dropping TA below 70.

 

[JamesW]

I would let it go down below 70. I think that if you just keep the pH at 7.8, and not raise the TA, then your pH will stop rising.

 

[ptbrunet]

OK, So add 14 oz MA every time it gets to 7.9 to drop it to 7.8 and eventually as the TA drops the pH should stay at 7.8? Or maybe I can use 32 oz to drop it to 7.6 each time until I see it stabilizing at 7.8.

 

[JamesW]

I would try to keep the pH as close to 7.8 as possible. And, I would try to keep the CSI in the -0.3 to +0.3 range. I would target -0.3 for the coldest that your water gets and +0.3 for the warmest that it gets.

 

[ptbrunet]

It would be nice to have a pH test kit that is more precise. My Taylor Basic test kit has color bars at 7.5, 7.8, and 8.2 so I'm always guessing about 7.6, 7.7 and 7.9. Maybe it's not a big deal.

 

[dschlic1]

I have had some experience with keeping the TA low and the pH at 7.8 or so. It does minimize the amount of acid needed, however I have found that the TA always creeps up. And as it creeps up so does the acid requirement. Then to reduce the TA requires large amounts of acid. So in the end I probably end up using the same amount of acid over a long period of time.