Brown Dust / Stairs

[RussH]

We've had the pool open for about two weeks and have had a continual brown dust problem gathering in the bottom of the pool. Test results are:

FC=7 ppm
CC= 0
pH = 7.6
CYA = 40
Alkalinity = 90
CH = 170

I've read a lot of the old posts with this problem and it seems to fit the same pattern as others. Only happens when the pump is running. Can pass an OCLT at SLAM levels, etc.

Today I pulled out the stairs from the pool and found the previous owner had weighed it down with a couple of broken up cinder blocks and one round piece of cement. The inside of the stairs was extreme filth and smelled really bad. Pictures are below. I vacuumed the mess out of the pool that got released when I pulled the stairs out, backwashed the filter and SLAMed to 18 ppm. Some more of the dust has accumulated since the slam, I brushed it and it later settled again, but it is still brown. I thought at this chlorine level, it would turn white. Should it not?

My main question is about the stairs. I assume he had the cinder blocks in to keep the stairs stable. Is this a typical type stair or is there something better? This thing is always going to have a dead space with uncirculated water trapped in it. The stairs have two handholds for lifting it on each side which may let some water flow through it with the circulation pattern in the pool. This may be where the dust has been coming from as what got unleashed getting the stairs out behaves like what I have been seeing.

Thanks,

Russ

 

[RussH]

Here's a picture of the stuff built up so far.

 

[Charlie_R]

I get a lot of that in my pool also. I don't have steps, just the ladder. It seems to be just airborne dust, and yes, it's a pain in the tail keeping the pool clean. Not much we can do about it. I usually let it go for a few days between vacuuming. I do have to clean my carts more frequently because of it.

 

[RussH]

I'm beginning to suspect that the stairs have been metering this gunk out into the pool, the chlorine kills it and it settles out as the brown dust. I released a LOT of it getting the stairs out. The pool got somewhat cloudy, I slammed it and have lost 3.5 ppm in 1.5 hours. I added bleach, vacuumed it again and the brown dust didnt return immediately and 45 minutes later still isnt back. That has never happened before with the pump running. The water is clearer than after the stairs were removed but not back to the clearest it has been. About to test FC again.

Russ

 

[Smykowski]

Those stairs are terrible. I have a similar set, and you're exactly right, it just creates a circulation dead spot. Just do your best to get back there and mix it all up once or twice a week.

I got rid of the concrete blocks and made some PVC anchors and that seemed to help, but because of the lack of circulation, junk still collects back there. I'm not sure there's any way to completely eliminate it.

 

[RussH]

Those stairs are terrible. I have a similar set, and you're exactly right, it just creates a circulation dead spot. Just do your best to get back there and mix it all up once or twice a week.

I got rid of the concrete blocks and made some PVC anchors and that seemed to help, but because of the lack of circulation, junk still collects back there. I'm not sure there's any way to completely eliminate it.

Is it supposed to have cinder blocks in it? What happens if there are no weights in the stairs, do they float?

It held at about 19.5 ppm (CYA=40) for the last 1.5 hours. It had dropped 3 ppm each on the previous two intervals. I'll check it again after dark and then before sunrise tomorrow. There is a little dust built back up, but the rate seems slower. Maybe... At any rate, whatever was in the stairs was living and needed removed/killed.

Russ

 

[Smykowski]

Yeah, without something to weigh them down, my stairs will float away.

 

[RussH]

Yeah, without something to weigh them down, my stairs will float away.

What are you using in yours? I dont think cinder block is the way to go. These had turned into a breeding ground. Think live rock in a marine aquarium. The block itself was also disintegrating.

Russ

 

[Charlie_R]

You can try several 2" PVC pipe sections filled with sand and capped on both ends. Stack as many as needed to hold the steps down.

Unfortunately, removal of the steps and cleaning will probably need to be done several times each season, with whatever you use to weight them down.

 

[Butterfly]

We had a member that cut 2" round holes in the bottom and sides of the steps to facilitate water circulation.

Then they brushed up and down, back and forth near the holes to push water into them. They said it made a huge difference in keeping that area clean. You could also use a water hose thru the holes to move the water and you could squirt some bleach in there, too.

 

[RussH]

I was thinking of PVC filled with sand. I'll weigh the stuff he had in there to see how much it will take. I think it had several seasons worth of gunk built up in it. Now that I know what is going on with it, I can stay ahead of it. Cutting holes in it is a good idea. I can put the hose in it when I add water.

The pool held 26 ppm overnight, CC<0.5 and its clear, so I guess I've killed whatever was in it. I pushed it to mustard shock level since it was close. There is a fair amount of brown dust back on the bottom. I'll vacuum it later, backwash and see what happens.

Russ

 

[RussH]

I tested the pool this evening and the FC had dropped to 13 ppm after passing the overnight test at 26 ppm with no drop. Other test parameters:

CC= 0
pH = 7.6
CYA = 40
TA = 90
CH = 170

The water looks clear. I even think that the accumulation of brown dust has slowed. We have had a lot of wind today (25-30 mph) blowing a lot of tree debris into the pool which I have kept skimmed out. It's been pretty sunny also. Any ideas what is going on?

Russ

 

[RobbieH]

That brown stuff is just the dust that is blown into the pool. I have the same thing, at least until the robot cleans it up.

 

[RussH]

That may be where the dust came from, but how can it lose 13 ppm of FC in ten daylight hours after passing the OCLT with no loss. Is there a limit to how much protection 40 ppm CYA can provide?

Russ

 

[jblizzle]

Why do you keep raising the FC level so high? That is just going to damage your liner. SLAM level for a CYA of 40ppm is 16ppm ... that is where you should be ... NOT up at 26ppm like you mentioned.

The CYA protects a certain % of the FC from the sun ... the higher you raise the FC level, the more ppm you will lose at the same %. That is another reason to not raise the FC so far above SLAM level, you are just going to lose more to the sun.

 

[TreeFiter]

At 40ppm CYA its normal to lose about 50% of your FC in a day.

 

[RussH]

I had read old theads here that suspected the brown dust could be related to mustard algae. So, when the gunk from under the stairs was released yesterday, I raised it on up to mustard algae shock level last night which it held. I was just surprised that it lost so much during the day today. It made me wonder if something else was going on, but I guess that much of a loss is normal.

Russ

 

[pwrstrk]

It's just that 26 ppm FC is way to much for 40 ppm of CYA. 26 ppm of FC is 2 ppm higher than SLAM level for 60 ppm of CYA.

 

[RussH]

Ok. I just surprised me when it dropped that much. Hopefully I've gotten all of the issues with this pool exposed now.

Russ

 

[Casey]

Did the brown dust go away Russ? As mentioned previously, those steps are notorious for algae blooms. They need pulled out at least 2x's a month and cleaned really well.