Water Exchange: Cleaning Pool at Same Time

Moeqt · Jun 4, 2020

Hello, due to my high CYA levels I am going to do a water exchange. My diluted CYA is 80, so actually 160. I have a 15000 gallon pool so plan to exchange 2/3 of the water using a submersible pump.

I have become perhaps overly ambitious now and thought that I might tackle some additional projects while there is less water in the pool. I have some staining and some yellow algae so I thought that I would do some scrubbing of the walls at the same time. Is there a link with the process for how to do this? Diluted Muric Acid? A particular type of scrubber? Is it safe to be in the water with the pump in the water?

I have a small spot of rebar peeking through the plaster where the pool builder did not cover. I had pointed it out to him and they were going to come back with a spot putty or some such, but he disappeared. Is there anything that I should put on this while the water is drained?

I plan to do this tomorrow, and would like to immediately disband with the chlorine tablets and powdered shock so that I don't get into this mess again. Is there a link for what to buy instead? I have searched the forums and it is a wealth of information but I want to ensure that I am reading the "right" link.

Thank you,
Maureen

splashpad · Jun 4, 2020

Moeqt said:
I plan to do this tomorrow, and would like to immediately disband with the chlorine tablets and powdered shock so that I don't get into this mess again. Is there a link for what to buy instead? I have searched the forums and it is a wealth of information but I want to ensure that I am reading the "right" link.

I have a vinyl AGP, so I can't help with all of your questions, BUT, I can help with this part

Sodium Hypochlorite is liquid Chlorine, aka Bleach

. You can use plain household bleach 6% on label, or try and source Pool Chlorine @ 10-12% (which can be found at Walmart and some chain hardware stores). You must check the date codes and the storage conditions of liquid chlorine (it does not tolerate heat/direct UV/sunlight)
You can use powdered shock (cal-hypo), as you have a plaster pool that needs calcium maintained

The tablets can used to add CYA if you dose in measured amounts (not for constant addition/management of chlorine)

mknauss · Jun 4, 2020

If you are doing a water exchange, the water level will remain the same. If draining, be very careful in Houston as a shallow water table could cause your pool to 'pop' out of the ground and destroy it.

I am not completely sure of what you wish to achieve with the 'cleaning'. Any algae needs to follow the SLAM Process with the pool full. Staining, if metals, cannot be addressed with chlorine. The putty to cover the rebar could be done, but there are products that can be done under water as well. Also do not mix acid and chlorine during this cleaning. That will create chlorine gas, which is toxic.

Moeqt · Jun 4, 2020

Thank you. Theoretically, how much water could be drained without pop up? I was thinking bring it down 1 to 2 feet out of 4 feet in the shallow end, scrub the walls, and then begin adding back in while I continue to pump.

mknauss · Jun 4, 2020

Hard to say. I would not like to give guidance as I do not know your water table. If you live along Buffalo Bayou it might only take a foot or less of water drop. If on a high point in N Houston / Katy it might be able to be fully drained.

What you plan will take several iterations to lower your CYA to an acceptable level.

I still do not understand what you think you will achieve with 'cleaning' that cannot be done when it is full. What do you expect to 'clean'?

Moeqt · Jun 4, 2020

Hi, I do live along Buffalo Bayou, and this is why I am interested in doing some extra scrubbing on the upper walls. I have some staining from the massive flooding from Hurricane Harvey. I do take your point, however, that I could address the stains once the pool is back to normal levels and my chemistry is under control. When you say that it will take several iterations to reduce CYA to acceptable levels, does that also mean with exchange? For example, the pool temperature is around 89 degrees and will be at 90 most likely by tomorrow. The tap water that I would be using to fill up the pool I have just measured around 74. So I plan to put the fill hose in the deep end, to the bottom, and put the pump on one of the steps in the shallow end. Can I effectively exchange sufficient water using this method in one effort, or am I best to do an exchange for one day, measure CYA, then run the exchange again the next day and measure CYA? At some point I would estimate that I will begin pumping out new water as it disperses and the temperature equalizes. I need to measure the output and input using the 5 gallon bucket test, which I will do when the pump arrives. Thanks again.

mknauss · Jun 4, 2020

A water exchange is the proper method, but you have been saying in earlier posts you were draining and refilling.

You do not show any Poolmath data but most likely it is proper to add water to the deep end and pull from the surface for a water exchange. During this, the water level stays full. You do not run your pool pumps, disable them via the circuit breaker. Determine how long it will take to exchange at least 75% of your pool volume using a 5 gallon bucket to determine gpm in/out.

Moeqt · Jun 4, 2020

splashpad said:
I have a vinyl AGP, so I can't help with all of your questions, BUT, I can help with this part Sodium Hypochlorite is liquid Chlorine, aka Bleach . You can use plain household bleach 6% on label, or try and source Pool Chlorine @ 10-12% (which can be found at Walmart and some chain hardware stores). You must check the date codes and the storage conditions of liquid chlorine (it does not tolerate heat/direct UV/sunlight)
You can use powdered shock (cal-hypo), as you have a plaster pool that needs calcium maintained The tablets can used to add CYA if you dose in measured amounts (not for constant addition/management of chlorine)

Thank you for this information. My issue is that I have sky high calcium and CYA, so I am leery of ever using those tabs again. My pool store sells the refillable jugs of liquid chlorine that they say does not add CYA. Are these acceptable replacements for household bleach and/or Pool Chlorine? They fill the jug, you use it and then bring it back for refills. I travel a lot and won't be able to add liquid each day, so in my preliminary reading here, I see salt water generators, and I am wondering if this means that I convert to a salt system, or I could use SWG for when I am away, and liquid bleach for when I am home. I will read more about this and appreciate any perspectives.