Acid Wash? Anything Less Drastic?

[HouseBroke]

I recently bought a house with an inground gunite pool in Northern California. The pool is probably forty years old or close but not in too bad shape, except for some pretty serious staining. Although the palster has a somewhat mottled appearance overall, it is only really bad on the shallowest part, where the built-in concrete steps are. I suspect the combination of shallow water, corner location and sunny side of the pool combined to make this the warmest spot, and therefore the most attractive for algae.

I have a pool service now (and apparently the sellers have used them since 2002) and there has not been any algae or other problems since I bought the house a few months ago, and I suspect not since 2002, so the stains have probably been there a long time.

I have spoken to two pool service companies about doing a power wash or an acid wash to try to get rid of the stains. Both have told me that a power wash will be ineffective and that they don't want to do an acid wash. Neither gave me anything that seemed to me to be a good reason not to try the acid wash. They both want to replaster the whole pool. I would like to hold off on that for at least a couple of years as I plan to do some other pool remodelling eventually, but don't want to do it right now.

The only reason not to do an acid wash that made any sense was that it might weaken the plaster and hasten its demise. But if I'm going to re-plaster in a couple of yers anyway, I'm not sure that's persuasive.

I would be interested in people's experiences with acid washes. They seem to have gone out of style. Can anyone tell me why?

Does anyone have any ideas for how I can treat relatively severe but localized staining short of an acid wash or replaster job? Would a power wash do any good? Is it worth trying to spray the area with a power washer wand without draining the pool? Since it is the steps, I expect the power washer hose could reach it all without draining any water.

[finishguy]

I recently bought a house with an inground gunite pool in Northern California. The pool is probably forty years old or close but not in too bad shape, except for some pretty serious staining. Although the palster has a somewhat mottled appearance overall, it is only really bad on the shallowest part, where the built-in concrete steps are. I suspect the combination of shallow water, corner location and sunny side of the pool combined to make this the warmest spot, and therefore the most attractive for algae.

I have a pool service now (and apparently the sellers have used them since 2002) and there has not been any algae or other problems since I bought the house a few months ago, and I suspect not since 2002, so the stains have probably been there a long time.

I have spoken to two pool service companies about doing a power wash or an acid wash to try to get rid of the stains. Both have told me that a power wash will be ineffective and that they don't want to do an acid wash. Neither gave me anything that seemed to me to be a good reason not to try the acid wash. They both want to replaster the whole pool. I would like to hold off on that for at least a couple of years as I plan to do some other pool remodelling eventually, but don't want to do it right now.

The only reason not to do an acid wash that made any sense was that it might weaken the plaster and hasten its demise. But if I'm going to re-plaster in a couple of yers anyway, I'm not sure that's persuasive.

I would be interested in people's experiences with acid washes. They seem to have gone out of style. Can anyone tell me why?

Does anyone have any ideas for how I can treat relatively severe but localized staining short of an acid wash or replaster job? Would a power wash do any good? Is it worth trying to spray the area with a power washer wand without draining the pool? Since it is the steps, I expect the power washer hose could reach it all without draining any water.

Do not drain it to acid wash it if its that old. If its a bad stain its NOT comming out. I would try and hire a company to use an under water polisher with a diamond pad. Guys charge quite a bit do do this, if you can find one. If your planing on re plastering it in a few years dont waste the money unless money is no problem. Acid wash will make your pool rough and rarely takes out stains. Take your pool brush pole, with out the brush and hold it on the stain under water and poor some acid down it. Hold it there for a few minutes and see if it helps.

[ANG]

If you want to try acid, Get a 2" pipe long enough to reach the stain then pour acid thru the pipe.

That will tell you if acid washing will work.

[HouseBroke]

Thanks Finishguy and Ang, I will try to the acid down the pipe idea.

Do you guys, or anyone elese, know about the "Drainless Acid Wash"? Basically, you leave the water in the pool and bring the PH level way down (I suppose by adding acid to the pool water) then scrub the bottom with a brush.

On the one hand, if a real, drain all the water, acid wash wouldn't do it, it seems very unlikely that this method will. On the other hand, any reason not to give it a try?

I would like to find a way to get some cosmetic improvement short of the full on replaster job. Money is an issue (Ok, OK, money is THE issue - if not, I would do the replaster job now).

[drip]

Hi, Jack's Magic makes some products that claim to be able to take out existing stains although the procedure to use them properly can be sometimes complicated. I have used some of their products and they do work if done properly and none require draining. search jacks magic and check out the products The Iron, Cobalt & Spot Etching Stuff™ and The Copper & Scale Stuff™. I have used both and they both work, you just need to determine what type staining you have.

[finishguy]

Thanks Finishguy and Ang, I will try to the acid down the pipe idea.

Do you guys, or anyone elese, know about the "Drainless Acid Wash"? Basically, you leave the water in the pool and bring the PH level way down (I suppose by adding acid to the pool water) then scrub the bottom with a brush.

On the one hand, if a real, drain all the water, acid wash wouldn't do it, it seems very unlikely that this method will. On the other hand, any reason not to give it a try?

I would like to find a way to get some cosmetic improvement short of the full on replaster job. Money is an issue (Ok, OK, money is THE issue - if not, I would do the replaster job now).

I do them quite a bit. It will eat the finish and make your pool rougher than it is now. There is more to it than just add acid and should only be done by a pro that knows the proper way,especialy if you have a heater. You live in an area with lots of pool pros, find someone to hit it with a diamond pad. Jacks magic is a very good product but most homeowners have bad luck with it. To me it sounds like OLD plaster. If you want the best way thats very inexpensive, do it your self. Drain the water to just past the area get a belt sander and be careful. Either it will come out or it wont. Watch what your doing and your not gonna hurt anything. Fill it as soon as your done, do not let it sit without water.Fill it asap, fill it asap, fill it asap, fill it asap, fill it asap, fill it asap. GOOD LUCK

[HouseBroke]

Thanks again, Finishguy. There are lot of pool pros around here, but it seems they only want to do big jobs, and a full re-plaster is on the low end of that. I am having trouble finding anyone willing to putz around with small stuff.

I am surprised at the suggestion of using a belt sander. It doesn't seem like it would get into the pores of the plaster very well. The plaster is not terribly rough, but its definitely testured. Wouldn't a wire brush work better? A power wire brush on a drill, or preferably, on a disk grinder? It seems like that would get down into the low spots a lot better.

[finishguy]

Thanks again, Finishguy. There are lot of pool pros around here, but it seems they only want to do big jobs, and a full re-plaster is on the low end of that. I am having trouble finding anyone willing to putz around with small stuff.

I am surprised at the suggestion of using a belt sander. It doesn't seem like it would get into the pores of the plaster very well. The plaster is not terribly rough, but its definitely testured. Wouldn't a wire brush work better? A power wire brush on a drill, or preferably, on a disk grinder? It seems like that would get down into the low spots a lot better.

A belt sander will sand it right off. It will sand the plaster right off also. All the other things will burn the plaster and make it ugly. A big 7 inch disk grinder with a flexible pad and sand paper is a great choice but be very careful. Its possible that you will burn the plaster, just lightly hit it. The plaster isnt as tough as you think and it will make grind marks. If the plaster is old and rough, the stain might be deep into the plaster. You will make a big ugly spot trying to get it out if it doesnt come right off.

[gulfstreampool]

I recently bought a house with an inground gunite pool in Northern California. The pool is probably forty years old or close but not in too bad shape, except for some pretty serious staining. Although the palster has a somewhat mottled appearance overall, it is only really bad on the shallowest part, where the built-in concrete steps are. I suspect the combination of shallow water, corner location and sunny side of the pool combined to make this the warmest spot, and therefore the most attractive for algae.

I have a pool service now (and apparently the sellers have used them since 2002) and there has not been any algae or other problems since I bought the house a few months ago, and I suspect not since 2002, so the stains have probably been there a long time.

I have spoken to two pool service companies about doing a power wash or an acid wash to try to get rid of the stains. Both have told me that a power wash will be ineffective and that they don't want to do an acid wash. Neither gave me anything that seemed to me to be a good reason not to try the acid wash. They both want to replaster the whole pool. I would like to hold off on that for at least a couple of years as I plan to do some other pool remodelling eventually, but don't want to do it right now.

The only reason not to do an acid wash that made any sense was that it might weaken the plaster and hasten its demise. But if I'm going to re-plaster in a couple of yers anyway, I'm not sure that's persuasive.

I would be interested in people's experiences with acid washes. They seem to have gone out of style. Can anyone tell me why?

Does anyone have any ideas for how I can treat relatively severe but localized staining short of an acid wash or replaster job? Would a power wash do any good? Is it worth trying to spray the area with a power washer wand without draining the pool? Since it is the steps, I expect the power washer hose could reach it all without draining any water.

I have done many acid washes here in Fla and not concerned about doing them, other than the discharge. A mild wash will not rough the surface that much. As mentioned before, the pipe trick will answer some questions. Also, when drained, give the pool a very good chlrine bath. I use Cal Hypo granules and let it sit on the pool for a day, sometimes two. This will kill all growth and whiten the surface. Really bad pools I've used commercial grade peroxide. These treatments are dangerouse and caution should be used. If you acid wash, make darn sure all of it gets wash and pumped out. Acid and chlorine is a no no. The gas it oriduces can be deadly. Oh, here in Fla we make darn sure we know where the water table is or your pool will become a boat. Good luck.

[twhite]

I would check the products from www.bio-dex.com ... They are quality and I use those as an alternate to acid washing.

[flexfitness]

Hi

I acid wash and diamond pad polish probably 20 to 30 pools per season...

I use a standard 20dollar garden pump sprayer to apply Muriatic Acid mixed with White 'n Brite on to the plaster.

Muriatic Acid to White 'n Brite Mix 10:1

If you have really bad stains that are dark green or black then mix like 10:2 or 10:3 and more then one application is required!

I take the pump sprayer put a application on the plaster, starting at the bottom and work up to the walls. let the acid mix

do its thing for about 5 to 10min and then pressure wash it with a pretty narrow tip. If that still doesnt take the stains out the next thing is go to a pool chemical supply store, get chlorine granulate and give a few scoops of it in the pumpsprayer that now is filled with water and shake it for mixing. Apply that just like the Acid mix put this time scrub it really hard into the stain and let it sit there for half an hour, then wash it off.

Now i take the diamond pad polisher and polish. With the polisher i use i can get it smoother than a fresh plaster trowl finish.

But i also have to admit that of all the pools i do a year there is always one that is in too bad shape to acid wash and polish. The stain on those have just eaten to bad into the plaster and the plaster is falling apart. the normal charge of pool polishing is about 3500 USD compared to replaster about 8000USD and the polishing gives you about 10 to 15 years if you take care of the pool chemistry..... Pools live or die by the poolchemistry!!!

Thanks alot

FLEX

[BajaPoolRepair]

Lots of professional advice here... but everyone was quick to remove layers after layers of your plaster, only one person hinted that your "stains" may be just "lack of" plaster. And what your seeing is the gray concrete behind the plaster. And if your plaster is that thin, after acid washes or years of service, or mistreatment of chems... then another acid wash or diamond sanding will ruin the whole thing.