Pool Water Changed Color After Acid Wash

by Linda

About 4 weeks ago, our regular pool maintenance guy suggested an acid wash for our 8 year old salt system pool. We trust him and agreed. The plaster is gray and white, which had previously given the water a medium blue color. The blue had lightened as the pool aged, and he (Dennis) said it would be somewhat darker after acid washing it.

He drained the pool and did the acid wash. However, when he refilled it, the water was VERY green in color. Looked horrible. There was a bit of an algae problem, which he quickly resolved, but the pool still looked green and cloudy. He then brushed the sides and vacuumed. Eventually, he was able to make the pool obviously clean.

The water is clear, there are no algae, and chemicals are all within normal range. Now, the pool looks green/blue, which is not a color I like. It is bluer than after it was first acid washed but still way too green. I miss the crisp clean blue color that it used to have. What would cause this color change?

He doesn't really feel it's due to metals but is using a weekly metal removing product to be sure all metals, esp copper are not the issue. The first dose went in yesterday, with the next due in a week. He also plans to power wash the pool and vacuum again.

I do not see or feel plaster damage. I hope you can comment on what might cause such a drastic change in the water color, and what can be done about it.

Thank you very much.

Thanks for the question Linda

Normally after an acid wash the plaster will become lighter instead of darker. I don't know why your pool guy would tell you otherwise, unless he did a test area and realized the plaster under the top layer of plaster was darker.

Most people do acid washes to brighten up their pools and make a lighter color.

It could be the plaster underneath was a lighter green/blue and that's what is coming through. I conferred with another well know pool guy and this was his response:

"My guess is the acid wash lightened up the grey plaster - not darkened it. Hence since it is lighter the Sun reflecting off of it will have a more greenish tint and less of a a dark blue. On cloudy days or early in the AM if the pool looks light grey then it is just the tint the Sun now produces."

I have never known the water to turn another color when an acid wash was done correctly. It may be as stated above, that the newly revealed plaster is causing the water to look a greenish/blueish.

If there are no metals in the water there's no need to use a metal sequestrant. It won't hurt to use it but is an unnecessary added expense.

If you'd like I can look at the chemical readings and see if there's something there. I need the actual number for that - Chlorine, CYA (cyanuric acid/stabilizer), pH, Alkalinity, Calcium Hardness, and Metals (iron and copper) and names of any algaecides you may have used along with clarifiers, phosphate removers, and/or flocs.

If they all check out the only other reason for the color change of the water would be the lighter color plaster.

If you feel your situation is more complex than this, I do phone consultations for a donation of your choice. It makes things go much faster and many people have found it extremely beneficial, saving them time and money in the long run. All your questions will be answered. I have nothing to sell you so you know I'm not bias.

Pool Consultation

Hope this helps and have a great Summer.


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How Do I Unclog Hot Tub-Swimming Pool Line

by Ronald

The gravity pipe from spa to pool is blocked. It has several 90degree joints.

Have tried flushing with a hose & vacuuming, to no avail.

What do you suggest?

Thanks for the question Ronald

I know this can be one of the most frustrating things for a hot tub and pool owner. Here are a couple of things I've used. Most of the time they've succeeded, but a few times I had to refer this to the local leak detection company I used.

A simple plumbers snake usually won't work because of the 90 degree angles.

You can use high pressure water. A normal garden hose won't work for two reasons. First, there's not enough pressure. 2nd, you can't get a tight fit around the inlet. Pool pros and tech normally have a hose specially designed to fit around the inlet or returns.

A portable pool pump/pool cover pump can also suck the debris out of the lines. As above, you need to get a good seal in the pipe or it won't work.

You can also try to get some back pressure as well by hooking up a tight fitting hose with pressure on the other end of the pipe. This way you have suction on one end and water pressure on the other pushing the debris out.

Swimming Pool Cover Pump

If this doesn't work, you probably need to get a pool tech in there to take a look at it.

Hope this helps and let me know how it turns out for you.


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Re-Caulking A Concrete Pool..Using TSP & Acid Wash..

by Anthony

I want to recaulk under the lip of my in-ground concrete pool. The old caulk has mold in it. I plan to TSP Acid wash and TSP again.

Will this take care of the problem so my new caulk job will look good.

Thanks for the question Anthony

The first step is to clean the surface with TSP (trisodium phosphate). A gallon of TSP used for pools will cover an area about 200 square feet.

Be sure to get all the mold and/or algae off before you start any caulking or repairs. Try to strip as much old caulking off the edges and seams as you can. The new caulking needs a clean seat to dry and cure.

I've used TSP a few times on pools in Arizona. Acid washing all or part of a pool is never fun, but sometimes it's needed. When using muriatic acid, be sure to always wear goggles, protective clothes, and long rubber gloves. Muriatic acid is corrosive very caustic.

Muriatic Acid

Remember when you do the repairs to use just enough to do the job right. I've had to re-plumb other people's mistakes and it takes twice as long to do the job a 2nd time.

I guess they thought that if you can screw something down and tight is good, then really really really tight is even better. Not true.

Hope this helps and good luck with your project


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