Product for submerged concrete faux rocks to prevent Algae?

Chad_in_TX

Active member
Jul 24, 2019
37
Plano, TX
Does anyone know of a product or any other idea to minimize algae buildup on the portion of rocks that are under the waterline? If doesn’t matter how much chlorine I put in the pool, as soon as high temps hit Dallas, these rocks become a nightmare. Meaning, literally the whole pool will be spotless with zero algae, but algae still will be embedded into these rocks. I literally have to brush them daily. And because they are so porous, it’s not simply a one or two pass brush with the wire brush, I have to be in the water and spend 10 minuetes on each section to get most of the algae off(but even then I literally can’t always get all of it). Sometimes I even use a chlorine puck to go over the rocks and then brush and I still can’t get it all.

I’m going to drain the pool a bit to put in a new light and I would love to be able to do something with this rock. Because it is the biggest beatdown ever. Because if I neglect it, that rock basically turns into just a slimey dark green pond on the rock.

I thought possibly of putting plaster over the rock, but I don’t know that it would even bond. I just need something that will prevent the algae from getting so embedded into the rock. I keep up with my pool brushing it daily,but having to spend an hour brushing the rock is just not fun.
 

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Does anyone know of a product or any other idea to minimize algae buildup on the portion of rocks that are under the waterline? If doesn’t matter how much chlorine I put in the pool, as soon as high temps hit Dallas, these rocks become a nightmare. Meaning, literally the whole pool will be spotless with zero algae, but algae still will be embedded into these rocks. I literally have to brush them daily. And because they are so porous, it’s not simply a one or two pass brush with the wire brush, I have to be in the water and spend 10 minuetes on each section to get most of the algae off(but even then I literally can’t always get all of it). Sometimes I even use a chlorine puck to go over the rocks and then brush and I still can’t get it all.

I’m going to drain the pool a bit to put in a new light and I would love to be able to do something with this rock. Because it is the biggest beatdown ever. Because if I neglect it, that rock basically turns into just a slimey dark green pond on the rock.

I thought possibly of putting plaster over the rock, but I don’t know that it would even bond. I just need something that will prevent the algae from getting so embedded into the rock. I keep up with my pool brushing it daily,but having to spend an hour brushing the rock is just not fun.
Chlorine is what you want. If you are maintaining the FC and CYA per TFP recommendations (and not trusting a pool store to test the water), you shouldn’t have any algae on the surfaces under the water line.


If you’re doing that already, post up some test results from one of the recommended kits and someone can make some recommendations.
 
Chlorine is what you want. If you are maintaining the FC and CYA per TFP recommendations (and not trusting a pool store to test the water), you shouldn’t have any algae on the surfaces under the water line.


If you’re doing that already, post up some test results from one of the recommended kits and someone can make some recommendations.
And I would agree..but why is it that it only affects the rocks, and not the plaster? Meaning ,if my chlorine levels drop because of the heat, and I get algae in the rock, why isn’t it affecting the entire pool. In theory, it should… and that’s why I go back to something about the rock and how porous it is vs. the plaster.
 
And I would agree..but why is it that it only affects the rocks, and not the plaster? Meaning ,if my chlorine levels drop because of the heat, and I get algae in the rock, why isn’t it affecting the entire pool. In theory, it should… and that’s why I go back to something about the rock and how porous it is vs. the plaster.
Algae can grab ahold of porous surfaces a bit easier I guess. But if there’s no algae in the first place, it won’t matter. Got some recent test results? TFP tends to have very different guidelines than other places for keeping algae away.
 
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Your porous stones sound like the same surface as what attracts black algae in worn plaster.

Treat it like Black Algea...

Pick at the black algae spots with some sort of physical method: wooden stick, wire brush, or, my personal favorite, weak pressure washer. Then, apply the strongest LC to those spots: pump sprayer, dump jug over the spot—more than once is better. Then run FC hot.

You have to disrupt the black algae. If you have less than ten spots, use a bamboo BBQ skewer. If you have more, a weak pressure wash will make quick work of it. Get in the pool with a mask and snorkel and have at it. Some do not like the wire brush method and think it is too aggressive.

For the pressure wash, something like a 2500 psi with a 15 degree nozzle. Or 3000 PSI with a 25 degree nozzle. Also distance from the plaster matters a lot. Get close enough to pop off the algae but not close enough to damage the plaster.

Also will depend on the age and condition of your plaster. In any case this method seems to be less aggressive than a wire brush.

Use common sense and be careful.

Then, apply the strongest liquid chlorine to those spots. Either dump it and let it flow over, or get a pump sprayer. Some have gotten lazier over the years and just dump. It uses more chlorine, but you probably need to raise your level anyway.

Run your FC at 20% of CYA for at least at least 4 weeks. That means, if your CYA is 50, you are running at no less than 10FC. You want to be no less than 10FC when you test. If you need to dose higher, so that you are >10 when you test, do that.

This is the part that sucks; run your FC CONTINUOUSLY on the high side, on an ongoing basis, at a minimum 15% of CYA to try and keep the black algae at bay. So if your CYA is 50, run at NEVER less than 8. Better to maintain 10 at all times.

The pool, swimmers and equipment is completely safe up to SLAM level for your CYA. (Slam level for CYA of 50 is 20FC).
 
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I have a very similar problem...possibly even worse since 1/3 of our water line is intended to look like bricks (sort of) so there deep crevices that we have to deal with. Sure, it's easy to say to always maintain your chemicals at perfect levels and there will never be algae. In reality we all let it slip down a bit at some point. My pool has never been green even a little bit but certainly has ended up with Cl below suggested minimum a time or two. Algae took hold in this stuff and there's no way for us to scrape it all out of those crevices. I recently did a drain & fill. I pressure washed the "rock" features as best I could and it's much better but the pressure washer still didn't get it all.
 
Your porous stones sound like the same surface as what attracts black algae in worn plaster.

Treat it like Black Algea...

Pick at the black algae spots with some sort of physical method: wooden stick, wire brush, or, my personal favorite, weak pressure washer. Then, apply the strongest LC to those spots: pump sprayer, dump jug over the spot—more than once is better. Then run FC hot.

You have to disrupt the black algae. If you have less than ten spots, use a bamboo BBQ skewer. If you have more, a weak pressure wash will make quick work of it. Get in the pool with a mask and snorkel and have at it. Some do not like the wire brush method and think it is too aggressive.

For the pressure wash, something like a 2500 psi with a 15 degree nozzle. Or 3000 PSI with a 25 degree nozzle. Also distance from the plaster matters a lot. Get close enough to pop off the algae but not close enough to damage the plaster.

Also will depend on the age and condition of your plaster. In any case this method seems to be less aggressive than a wire brush.

Use common sense and be careful.

Then, apply the strongest liquid chlorine to those spots. Either dump it and let it flow over, or get a pump sprayer. Some have gotten lazier over the years and just dump. It uses more chlorine, but you probably need to raise your level anyway.

Run your FC at 20% of CYA for at least at least 4 weeks. That means, if your CYA is 50, you are running at no less than 10FC. You want to be no less than 10FC when you test. If you need to dose higher, so that you are >10 when you test, do that.

This is the part that sucks; run your FC CONTINUOUSLY on the high side, on an ongoing basis, at a minimum 15% of CYA to try and keep the black algae at bay. So if your CYA is 50, run at NEVER less than 8. Better to maintain 10 at all times.

The pool, swimmers and equipment is completely safe up to SLAM level for your CYA. (Slam level for CYA of 50 is 20FC).
Thank you for the post. Will do as suggested. I did leave out that when I brush even now, it’s with a snorkel mask and wire brush. It’s just a beating.
 
I have a very similar problem...possibly even worse since 1/3 of our water line is intended to look like bricks (sort of) so there deep crevices that we have to deal with. Sure, it's easy to say to always maintain your chemicals at perfect levels and there will never be algae. In reality we all let it slip down a bit at some point. My pool has never been green even a little bit but certainly has ended up with Cl below suggested minimum a time or two. Algae took hold in this stuff and there's no way for us to scrape it all out of those crevices. I recently did a drain & fill. I pressure washed the "rock" features as best I could and it's much better but the pressure washer still didn't get it all.

Looks cool if you’re coming over, but daily maintaining, I just wish it was all plaster into the water. Glad someone else can feel the pain.. lol
 
I may have missed it, but what are your chlorine and CYA numbers?

TFP has published FC target levels but that is for most pools. Ones with unique situations like poor circulation, rough spots, etc. may need more chlorine.
 
I may have missed it, but what are your chlorine and CYA numbers?

TFP has published FC target levels but that is for most pools. Ones with unique situations like poor circulation, rough spots, etc. may need more chlorine.
I get it. The pool also gets full west Sun all day and there are no trees. That obviously doesn’t help. But it gets to a point where I’m dumping big bucks in chlorine, combined with the cleaning headache. I guess it just is what it is and a lousy setup for a pool for tx heat. Was just hoping for a solution to modify the pool rock in some way vs. more $ towards chlorine and more time cleaning…
 

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