Sand Filter vs. Sediment - Need Help

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Chappy

Chappy

Well-known member
May 28, 2008
71
Central Texas
Time to solve this mystery that has been plaguing our pool for the past 2 years. There is a fine layer of sediment that builds up around the edge of the pool pretty much every day. If I brush it up, the water turns cloudy, and the next day after filtering it's sitting on the bottom like a brown halo.

I've been holding a FC level of about 17 for the past week, so I don't think it's algae.

Is it sand? Is it time to replace the sand in our Tagelus TA40D? I did flush it out with a hose a few seasons ago.

Not sure what the problem is but I'd love to get rid of this constant sedimentary companion.

Thanks!

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I am curious about this as well. I get this same stuff at the bottom but I have a cartridge filter. I have vacuumed mine out and it just seems to come back. The only though I have is loose dirt getting blown into the pool and settling at the bottom.
 
If it were occasional or seasonal depending on the prevailing winds I might think West Texas dust, you are a couple of hundred miles or so(?) east of the region where it coats everything, but that is not to say that if the wind is blowing right that you would not get some in Austin.
 
Dave, here are a complete set of test results. These are all done with brand new chemicals that I ordered last month :) The only tricky one is the CYA test. Ironically last week while I was trying to measure it, I totally lost the slender beaker! So for this test today, I used a crude method of filling the regular plastic cylinder instead until I could no longer see the bottom. It dissappeared at about 30ML (I dumped in an entire bottle of stabilizer bought at Home Depot last week - something I do every season).

Another note, I have twice recently gone around the edges and vacuumed the offending sediment straight to waste, but it reappears. And yes, I am brushing the walls often.

Here are the results minus CYA which I discussed above:
FC = 18
CC = 1
TC = 19
PH = 7.5
T/A = 290
CH = 200

Thanks!
 
Chappy said:
Not yet. Since I just did my first actual test with new chemicals last weekend, I've just been kind of dumping in jugs of bleach 3 and 6 at at time. Maybe I need to take a more concentrated effort?
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Yep, follow the shock process in Pool School and get that under control.

What does that stuff feel like? Sand will feel gritty, algae will feel slimy & pollen feels squishy.

I recommend a good filter cleaning like described here: my-sand-is-channeled-how-to-fix-it-t7626.html

You can also put a sock over the returns to see if sand is coming back into the pool from/thru the filter.
 
Maybe I need to take a more concentrated effort?
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My guess is it's dead algae and you need a more precise effort. Get your CYA test where you can use it. Then, when you have a decent CYA result, I think you might find your CYA is too high and, as a result, your chlorine has only been partially effective.

Like Butterfly and Woody, I think you need to clean your filter well and probably take your FC much higher. Get some of that stuff in your hand and see if it's gritty. I think it'll be slimy....dead algae
 
I do think it's dead algae, it was slimy to the touch. I took the hose to the filter and cleaned it out for about 15 minutes until it ran clear, and then I upped the FC to about 38. Seemed to pretty much hold there over night. I've also had the pump running continuously.

This may be a dumb question, but if it's all dead algae, how does shocking the pool get rid of it? (as opposed to live algae).

And should I run the pump continuously for a few days until it's all sorted out?

Thanks again.
 

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but if it's all dead algae, how does shocking the pool get rid of it?
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Dead algae comes from live algae which is still in your pool. You must shock (and you must follow the shock process article precisely) or you will continually have dead algae junking up your pool. In short you are not killing it all.
 
I agree with the others. It's probably dead algae. If it looks like the dust bunnies under the bed, just in water, and it disintegrates when you brush it...it's algae. And if the water's clear, but this stuff keeps forming, you're right on the threshhold. You are keeping it at bay, but not killing it all. Take off for the weekend, or get a hot spell, and you'll probably find a green cloudy pool.
 
Here's an update to my shock treatment over the weekend. Got the new CYA measuring tube and got an accurate reading before proceeding. Here were my pre-shock (Saturday) numbers:
PH: 7.5
FC: 10
CC: .5
CYA: 55
TA: 280
CH: 300

I brought the pool up to about a 25 FC level throughout most of the day and brushed the walls. Then I had it up to 28.5 FC in the evening. In the morning, I recorded a FC level of 33. I have been running the pump continuously and brushing the walls.

Just took a reading (Monday evening) and had a FC of 17 and a CC of 0.

The water is looking better, with less and less of the dead algae to brush up each day. But when I do brush the pool, it gets pretty cloudy, like there's a thin layer of the stuff still covering the bottom of the pool.

So can I safely assume that there's nothing alive in the pool and that I should just keep brushing and running the pump until the water sparkles? (seems like I'm still a ways off from sparkle though... I'm more at a less dingy state I'd say)

Thanks.
 
If it was done correctly, it is impossible for the FC to have increased.

Either the water was not properly mixed before the Sat. night test, or chlorine was added after the Sat night test.
Make sure to test at least an hour after any chemical addition.

I would re-do the OCLT tonight to be sure.
 
I did think that was odd - I probably took the test too soon after adding my last gallon of bleach for the day and it didn't properly mix.... I'll do another check tomorrow morning to see how it compares with my reading taken this evening. I'll get this precise shock process down if it kills me!
 
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