Stained Gunnite

[Gatchek]

Hi folks. New to the forum, but I've spent the last couple of days reading posts from this forum, and it sounds like an incredible wealth of knowledge. Here is the background:

I just bought a house that came with a 20,000 gal Gunnite pool with a DE filter running Fiberclear. My estimate is that the pool is about 20 years old. The previous owner used Baquacil. But I recently converted to Chlorine. The gunnite is white, with lots of (brownish) stains all over the walls and bottom. At first, I just thought it was algae and then when my robot (polaris 9300) didn't pick any of it up, I went into "research mode." From what I can tell, they are most likely "metal stains." I'm not sure if they are copper or iron. I also have NO idea how long they have been there. I also have quite a few tannin stains from leaves and acorns, as my pool is SURROUNDED by trees. My water test results are below:

FAC: .05 (I know its low, I'm in final stages of converting from Baquacil)
TC: .5
Combine Chl: .45
TA: 105
PH: 7.6
CH: 212
CYA: 22
Copper: 0
Iron: 0


Here is what I have done so far. I went to my local pool store and they gave me some "Stain free", which I was told was vitamin C. I added 1.75 lbs to the edge of the pool and to the steps, and didn't see a change at all in the color of the stains. At the time, I had very little chlorine in(refer to the levels above). My next thoughts are to do an Ascorbic Acid treatment with sequesterants based on the success stories on this forum. My question is that if the "vitamin c" treatment didn't help, would Ascorbic acid treatment do anything? Or do I just need to add more? Any ideas? I want

Thanks for taking the time out of your day to help!!

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[woodyp]

Try and crush up your own vitamin C tabs in a knee high and hold it there for a couple of minutes or so.

 

[Gatchek]

Try and crush up your own vitamin C tabs in a knee high and hold it there for a couple of minutes or so.

I'm assuming that this would determine if a "concentrated" forumla would work or not... correct? Because it would probably take me years to remove the stains using that method Being that the entire pool is covered in them.


Also, where would I find such "vitamin C tab"? the stuff I got from my pool store was in ganulated form.

 

[DCAG]

Try and crush up your own vitamin C tabs in a knee high and hold it there for a couple of minutes or so.

I'm assuming that this would determine if a "concentrated" forumla would work or not... correct? Because it would probably take me years to remove the stains using that method Being that the entire pool is covered in them.


Also, where would I find such "vitamin C tab"? the stuff I got from my pool store was in ganulated form.

Those would be regular vitamin C tablets from a grocery store. Make sure the ingredients say Vitamin C "as ascorbic acid"

Some vitamin C is from Rose Hips, and I don't think that's the same thing.

Dan

 

[Gatchek]

Try and crush up your own vitamin C tabs in a knee high and hold it there for a couple of minutes or so.

I'm assuming that this would determine if a "concentrated" forumla would work or not... correct? Because it would probably take me years to remove the stains using that method Being that the entire pool is covered in them.


Also, where would I find such "vitamin C tab"? the stuff I got from my pool store was in ganulated form.

Those would be regular vitamin C tablets from a grocery store. Make sure the ingredients say Vitamin C "as ascorbic acid"

Some vitamin C is from Rose Hips, and I don't think that's the same thing.

Dan

No luck. The vitamin C didn't do anything. I might just look into painting it next year. On a separate note... or maybe not.... I can't get my filter to stay clean. Again... I have so many variables going on right now. Like I mentioned, I just converted from Baquacil to Chlorine, and my filter keeps getting massively clogged. I will pull out the grids... hose them down... put them back in with fresh Fiberclear, and the pressure is about 8-10 psi. It will rise to about 25psi in about 4-5 hours. I can backwash it, and bring it back down to 12 psi.... but that only lasts about 3 hours before its back up to 25psi. So far, I have cleaned the grids 5 times in the last week.

Here are my questions:
Was the water really that dirty?
Is this part of the Baquacil -> Chlorine conversion process?
What exactly is the yellow/orange stuff my filter is getting clogged with?
Does the orange junk in my filter have anything to do with the orange/brown color on the bottom and sides of my pool?

Thanks again! I'm not about to go broke from this darn pool. We bought the house in the winter time, and didn't get to see the pool until we bought the house. The wife wants to fill it in, but I know it can be saved. Please help me prove her wrong.

Here are the pictures of the filter AFTER they get clogged.
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[DCAG]

It doesn't look like you've completed the conversion from Baq yet. Are you following the TFP method of conversion from here?

I'd worry about the stains after you're sure there's no more Baquacil in the pool.

Dan

 

[Gatchek]

It doesn't look like you've completed the conversion from Baq yet. Are you following the TFP method of conversion from here?

I'd worry about the stains after you're sure there's no more Baquacil in the pool.

Dan

Before I started the conversion process, my local pool store did a water test and confirmed that there was 0ppm of Baqua in the water. So, I assumed there was no more left in the pool, but I guess even a water sample could be wrong. I also soaked my DE filter in Muriatic acid for about 24 hours to ensure there was no baqua still in the filters.

 

[Gatchek]

It now looks like the filter has stabilized itself, after about 6 cleanings..... but those awful stains are still there....

 

[DCAG]

It now looks like the filter has stabilized itself, after about 6 cleanings..... but those awful stains are still there....

Having a vinyl liner, I can't help you too much with the stains. If you post another set of test results, someone with a Gunnite/plaster surfaced pool will chime in, I'm sure.

Dan

Edit: While looking at your last photo, I thought "Gee, those stains look a lot like trees... and a person taking a picture!" oops

 

[Gatchek]

I tell ya. Everywhere I go, that stain follows me. Hahaha. I'll do another water test and post the results. My problem is that I have no idea how old these stains are. They could be 12 years old. Who knows. Can I really get 12 year old stains up? Why couldn't they just have installed a liner or painted the gunnite blue? That's like wearing a white dress to a hotdog eating contest. It's going to get stained.

 

[JasonLion]

Paint never lasts very long.

The filter problems are all from the baqua conversion not getting done. You may well need to replace your grids if too much baqgoo solidified on them.

The next step on the stains is to try putting a trichlor tablet on a stained area for a couple of minutes and see if that makes any difference.

 

[Gatchek]

Paint never lasts very long.

The filter problems are all from the baqua conversion not getting done. You may well need to replace your grids if too much baqgoo solidified on them.

The next step on the stains is to try putting a trichlor tablet on a stained area for a couple of minutes and see if that makes any difference.

Thanks for the heads up on the baqua. I planned on replacing the whole system soon anyway. Now I have a better reason. I'll do the trichlor tablet test and report back. Thanks again for everyone's help.

 

[Gatchek]

Paint never lasts very long.

The filter problems are all from the baqua conversion not getting done. You may well need to replace your grids if too much baqgoo solidified on them.

The next step on the stains is to try putting a trichlor tablet on a stained area for a couple of minutes and see if that makes any difference.

Unfortunately, the trichlor tab didn't have an effect on the stains. What do you suggest next?

 

[danivdp]

Paint never lasts very long.

The filter problems are all from the baqua conversion not getting done. You may well need to replace your grids if too much baqgoo solidified on them.

The next step on the stains is to try putting a trichlor tablet on a stained area for a couple of minutes and see if that makes any difference.

Unfortunately, the trichlor tab didn't have an effect on the stains. What do you suggest next?

How long did you leave it there? I get tannin stains in my pool that go away after a week or two, faster if I bring pool to shock level......Leave the tab sit there for at least 24hrs, maybe a few days.

 

[holubec37]

My pool was stained darker than yours when I bought my house and drained the "lagoon". We chose to paint the pool as a temporary fix and plan on re-plastering next summer or the next. I tried the acid wash in addition to everything else trying to get the stains out before painting.

As far as the Stain Free treatment...I just did one on my pool. The stains were fresh enough that it worked quickly, but when I added the metal sequestrant, the pool got really cloudy. After some research, I found out that that was going to happen. Just be patient and let your filter do the work. The asorbic acid from the Stain Free will eat up your chlorine, so you need to stay on top of your chlorine levels until the asorbic acid is out of the water.

When my pool clouded up four days before the Father's Day pool party, I threw everything in the pool except fill dirt. Remember to be patient, and stay on top of the metal in the water if it's a problem for you.

Hope my past experience is of some help to you.

 

[Gatchek]

Thanks for the advice so far. I tried putting the trichlor puck on the stains for about 30 min. I'll try letting it sit for about 24 hours. Thanks for the advice. I think the hardest thing is to be patient.

 

[applgrl]

My gunnite is very old, so we live with the mottled look. I wouldn't recommend painting it. The paint is expensive and needs to cure for many, many days. If you let the paint cure properly, you risk the gunnite becoming too dry and cracking off the walls. If you don't let the paint cure properly, it bubbles up and/or leaves everybody with blue/white feet. As well as some interesting chemicals in the water.

If you are going to drain it at any point, I have some advice. Once the pool is empty, pour regular bleach from under the tile line down the walls, coating the whole wall as you go. Let it sit for an hour and bake in the hot sun. My pool goes about 3 shades whiter from this treatment. It's hard to tell from your photos how bad the stains are, but my guess is that if you keep your chlorine levels up and brush the walls/floor regularly, the staining will diminish.

If you are NOT going to drain it, AND you see improvement with the trichlor puck test, then I would start using cal-hypo as your chlorine of choice (until your calcium level gets near the top of the range.) Turn off your pump overnight, and sprinkle a section at a time with a light layer of cal-hypo. In the morning, turn the pump back on and scrub that area with a metal pool brush. It might take awhile, but the bleach should do it's job.

Another tip with a gunnite pool is to occasionally get into the pool with a garden hose, gun nozzle on, and spray the walls while you're in the pool to remove old dirt/algae etc. (Make sure you're not removing any gunnite tho!) This lets the chlorine do it's job since you remove the biofilm that "hides" algae, and might help lighten the stains.

Long run, I'd put in a properly sized sand filter. Simple, cheap, effective, especially with lots of trees around.

 

[Gatchek]

My gunnite is very old, so we live with the mottled look. I wouldn't recommend painting it. The paint is expensive and needs to cure for many, many days. If you let the paint cure properly, you risk the gunnite becoming too dry and cracking off the walls. If you don't let the paint cure properly, it bubbles up and/or leaves everybody with blue/white feet. As well as some interesting chemicals in the water.

If you are going to drain it at any point, I have some advice. Once the pool is empty, pour regular bleach from under the tile line down the walls, coating the whole wall as you go. Let it sit for an hour and bake in the hot sun. My pool goes about 3 shades whiter from this treatment. It's hard to tell from your photos how bad the stains are, but my guess is that if you keep your chlorine levels up and brush the walls/floor regularly, the staining will diminish.

If you are NOT going to drain it, AND you see improvement with the trichlor puck test, then I would start using cal-hypo as your chlorine of choice (until your calcium level gets near the top of the range.) Turn off your pump overnight, and sprinkle a section at a time with a light layer of cal-hypo. In the morning, turn the pump back on and scrub that area with a metal pool brush. It might take awhile, but the bleach should do it's job.

Another tip with a gunnite pool is to occasionally get into the pool with a garden hose, gun nozzle on, and spray the walls while you're in the pool to remove old dirt/algae etc. (Make sure you're not removing any gunnite tho!) This lets the chlorine do it's job since you remove the biofilm that "hides" algae, and might help lighten the stains.

Long run, I'd put in a properly sized sand filter. Simple, cheap, effective, especially with lots of trees around.

Thanks for the great advice. I definitely didn't want to paint it if I didn't have to. I think the pool was neglected for some time... so maybe what it needs is just a lot of time and patience. I'm sure it took a while to turn ugly... so it may take just as long if not more to make it pretty again.

I have a stainless steel brush, so I'll continue to give it some light brushing every now and again and try and record the results. Its hard to tell if the stains are getting lighter, or I'm just getting used to them.

 

[applgrl]

Yeah, sometimes it's good to live with it for awhile and gather more info before investing in a reno. I wouldn't trade my "ugly" pool for the on-going $6000 expense (my neighbour) and hassle of replacing a vinyl liner every 5-7 years. The old gunnite pools are deeper, you have more traction, and they are more durable IMHO.