White stuff around edge of pool

[BrianWilson]

I am a new pool owner and I have an issue. Around the waters edge of the pool right above the water there is a white line which I am assuming is some sort of calcium deposit (see picture). Since it is rock and not smooth I imagine it will be difficult to remove.

What is the best way to clean this? The pool has required very little maintenance all summer but the ph did get a little high (8.2) recently. Would this happen because of the ph being high?

Thanks,
Brian

 

[PoolOwnerNumber9]

A high pH could cause the deposits if your other readings were also high. Use vinegar and a scrub brush to test a small spot to see if that would remove the deposits without any adverse effects to the stone. Or you could use a dilute mixture of muriatic acid to test a small spot. Rinse well. Wait 24 hours after the test and recheck the test spot for any adverse effects to the stone. Start with a 10 to 1 mixture of acid and increase the strength if needed. If either one gives satisfactory results, then use that to clean the rock. You want to be very careful and use the minimum amount possible and rinse very well. You could use a dilute mixture of water and baking soda to scrub the stones to neutralize any remaining acid. Rinse well.

1) What are your other chemical readings?
2) What is the rock made of?
3) Do you know how the scale got so high up on the rocks?

 

[chem geek]

Brian, welcome to Trouble Free Pool!

 

[BrianWilson]

Thanks for the response. In answer to your questions:

a) I only have a simple strip test. PH is at 7.4. Chlorine is at 3ppm. Alkalines are at 210. I just ordered a proper test kit from here so I should have more readings once I get that.

b) I'm not sure of the type of rock. The pool was here when we bought the house.

c) It looks to me like the water soaks into the rock some and the scale starts at the top of where that is.

I will definitely try your suggestions starting with the vinegar. Would power washing be an option?

Thanks,
Brian

 

[PoolOwnerNumber9]

You could try a power washer. That might work. Be sure to get a "non-marking" hose. The standard black hose leaves black marks everywhere.

 

[dirty_steve]

Brian - I'm in the Austin area as well. Do you have a SWG? I have some rock similar to that around some flowerbeds and I believe it's a sandstone, which is extremely porous. I would assume that it's simply the stone absorbing the hard water and leaving a ring. Some of the stones that I have around flowerbeds even have faint white marks which I can only assume come from the sprinkler system and our lovely hard water.

 

[BrianWilson]

Thanks for the clarification on the rock. I don't have an SWG but I definitely have hard water as I am on a well (off of Hamilton Pool Rd.). I also read somewhere else that using glass beads might be an option. Harbor Freight has a pretty cheap setup that I might try if the other suggestions don't work. Another option I read about was to try using a pumice stone. Sounds labor intensive but I'll do it if it works.

Thanks,
Brian

 

[Plankton]

I don't mean to hijack this thread, but I have the exact same problem. My rock is flagstone, I don't know if that is any more porus or softer then sandstone, but anyway here is what I have done so far. I have tried the pumice stone trick, forget it, I got to one piece of rock and half the pumice stone was gone and the calcium was still there. I tried using a wire brush, no difference, then on the outside of the pool I tried CLR, I hate to say it but I've never been impressed with that product and I'm still not, it didn't even make a dent.

Okay, to move on, I tried a brass wire brush hooked up to my drill motor (this was in the spa, and I had drained all the water out) while this made a small difference it was very time consuming and I still could not get all the calcium deposits off, that stuff is extremely hard, it also did not hurt or discolor the stone, but I do want to try and polish out some of the areas I worked on. Next I tried a mixture of muratic acid, a small wire brush, elbow grease and a very small screwdriver. This worked better then anything else I tried, but still very very time consuming. I only have about an eighth of the spa done.

The small screwdriver was for chipping off the calcium, I felt like a dentist!! But I didn't hurt the stone, the mixture of MA and water seemed to work but frequent rinsing due to me worrying about hurting the grout. Other than that I just bought a product from Home Depot which is specifically made for cleaning hard water stains. It is a very strong concentration of Hydrochloric Acid. I have not tried this yet, since I tried the MA first and it did not work that well. I also tried the vinegar trick, that was no help. I did not know Harbor Frieght had a glass bead setup, that might just be my next item to try. So there you have it from my personal experience, if all else fails I will just go back to the MA, wire brush and screwdriver. If I come up with anything that does work I will be sure to post it here!

 

[JasonLion]

Alkalines are at 210

I assume that by "Alkalines" you mean total alkalinity. 210 is very high and will tend to increase calcium deposits. Some mild/slow discoloration/scaling just above the water line is normal, but high total alkalinity, high calcium, and high PH will all accelerate the process.