What is correct way to add acid to pool?

My pH is drifting up and I'll need to add some muriatic acid. What is the correct procedure? Do I add thru the skimmer? I have a vinyl pool with SWG-is the dry acid better for this? How long should I run the filter after adding? Can I put my solar cover on soon after adding? How long do we wait to test again and how long after adding can we safely swim?

Thanks!!

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Originally Posted by poolbee

My pH is drifting up and I'll need to add some muriatic acid. What is the correct procedure? Do I add thru the skimmer?
Do NOT add acid through the skimmer. This could damage your pump, filter, heater, and other parts plumbed into your equipment. Either dilute the acid in a big bucket of pool water, always adding the acid to the water and NOT the other way around, and distribute it around the pool or pour the acid SLOWLY into the stream of one of the returns going back into the pool if it is not too close to the skimmer.
I have a vinyl pool with SWG-is the dry acid better for this?
Muriatic acid is my first choice over dry acid but dry acid is fine. It is easier to work with but more expensive and add sufates to the water. Muriatic acid only adds chloride ions which reform as salt when they combine with the sodium hydroxide that is produced by the SWG, thus completeing the cycle of salt to chlorine back to salt again!
How long should I run the filter after adding?
Run it long enough to turn the water over in the pool at least once...for most pools this is about 4 hours. It also helps to brush the pool after adding acid or any other chemicals. This helps to mix and distribute it faster (and pools are never overbrushed....most are underbrushed so brushing is a good thing to do anyway).
Can I put my solar cover on soon after adding?
See above
How long do we wait to test again and how long after adding can we safely swim?
for retesting, ideally 24 hours since a lot of chemistry is happening when you adjust pH. If you want a rough idea give it a few hours but it may be different the next day!
As far as going in the water, give it a few hours and test. If the pH is ok then you can swim. It might be different the next day however so retest and readjust if needed.

Thanks!!

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I ususally try to add acid in the morning and test it in the afternoon if I want to swim the same day. Hope this helps

Thanks for the info.

Waterbear,

If I understand your chemistry lesson(And I was never good at chemistry!), using Muriatic Acid will raise my salt level? It is already running at 3,200 and I would like it lower. Would using another acid(ph down or another if there is) not raise the salt in my pool?

Thanks again!

It will not raise the salt level...it will maintain it. When the salt water generator generates chlorine it breaks down the salt into chlorine and sodium hydroxide (lye). This is what causes the pH to rise. When you add muriatic acid (HCl) it neutralizes the lye and reforms the salt and also forms water. If you use dry acid this does not occur and you will be creating sufates in the water which can cause problems if they build up too high.

Why do you want to lower your salt levels....3200 ppm is perfect as far as most manufacturers of SWGs say. Lowering the salt concentration will cause the cell to have to work harder to generate chlorine and will shorten it's useful life! I actually run my salt levels closer to 3400 ppm for this very reason. In terms of cell life it is better to run the salt a bit higher than lower! The cell is not a cheap item to have to replace!

I would like to try my salt at around 3000. That is what is recommended. I will be bringing my water to my pool builder this week for testing. Ben's salt test is giving me a reading of 3200 but my Autopilot is telling me 3700. My water has a very definite salty taste-much saltier that the water we tasted at the builders. I suspect the Autopilot is closer to the accurate number because the purifier is almost always off and when it is on I can run it at 15-20 but my chlorine levels run at 5/5.5 and my CYA reads in the low mid 40's.My cell is on level 2. Someone suggested I lower it to lever 1 and raise the output? Right now my numbers are all very good so would you suggest this? These are my numbers after adding the muriatic acid yesterday:
FC 5
CC 0
pH 7.4
ALK 110
CYA 45
temp 84

I only tested Cal once in the beginning because I have a liner pool. It was 170.

So if I am understanding, and as I said, chemistry isn't my forte, The SWG can run so low because the salt is high? Temps have been steady at about 83-84. I just think the salt taste is too strong. I though it was supposed to be slight.

First thing I would do is bump up the cya to the recommended 60-80 ppm. From everything that I have been able to find out (and from what I have seen in my own pool and in the water testing histories of my customers with SWGs the higher cya levels do make a difference because of the way the chlorine is introduced into the pool with a SWG as compared to manual chlorination. I would have the salt level checked at a pool store or with an Aquacheck salt test strip (they actually are pretty accurate!) and see what readings you get. It is possible that the PoolPilot is off calibration and can be recalibrated to a known accurate salt reading. As far as the adjustments, I am not that familiar with the with the Poolpilot settings but perhaps PoolSean will chip in and get you straightened out! You might want to start in thread in the Chlorine Feeders and Salt Generators section asking how to set the unit up. I know he monitors that one!

Thanks Waterbear for all your help and information. I am planning to get the water testing tomorrow. The way my water is now is how the pool co. set it up. I have only added acid.
Thanks again.