Brown gunk on the bottom of pool

[rox29160]

I am not aware of having any algae. My pool has always been crystal clear until this stuff started settling out a couple of weeks ago. After vacuuming last night, the stuff had settled back out again this morning.

Thanks for the advice BigDave. I had been wondering how to rig a makeshift filter onto my vaccum. I saw another thread where somebody used the stuffing out of a pillow, a bucket and a sump pump to filter iron out of their pool. Whether this is iron, algae or whatever, I need a makeshift filter to hook to my vaccum that will catch this "gunk" and not allow it to disperse back into my pool. I think the particles may be too small for even a nylon stocking. They seem to dissapear when you disturb them or try to touch them.

[famousdavis]

I used to have an Intex above-ground pool for years, with the same problem you've described. The problem wouldn't occur at the beginning of the summer, but by late July, the problem would appear every year. Turns out it was *pollen* that was collecting in my pool water! The only way I dealt with it was either empty out the pool every few weeks, or use a pool cover.

[rox29160]

Alright, I have finally decided to post my test results after receiving my new K2006 test kit. I've had it for a couple of weeks, but wanted to make sure I was getting consistent results before posting them on here. I still have the brown stuff settling on the bottom of my pool every couple of days. (Vinyl Intex above ground, approx 5,000 gallons, Intex SWCG)
Test 1 (WEEK 1)
FC 2.6 ppm
CC 0.2 ppm
PH 7.2
TA 90 PPM
CH Test started Purple instead of red
CYA DOT did not disappear

I added 1/4 pound more of cyuranic acid and waited a week before testing again.
test 2
FC 2.5 PPM
CC 0 PPM
PH 7.2
TA 80 PPM
CH 50 ppm ?
CYA Dot still did not disappear but solution is at least blurry this time. I would guess it probably around 15 ppm.

Regarding the Calcium Hardness, I tried a couple of different things. Per the instructions of the K2006 kit, I tried adding 5 drops of titrant first to tie up the metals in the test sample then the buffer and indicator. Doing this the solution was blue before adding any more titrant. Then I tried adding only 3 drops of titrant to tie up the metals before starting the test. Doing this, the solution started red and I was able to conduct the test until the solution changed from red to blue. This way yielded 50 ppm, but I don't understand chemistry so this may not be acceptable at all. Some body please advise.

Since the CH test started out purple does this mean that I need something to take the metals out of my pool water? I have about another 1/4 pound of cyuranic acid. Should I go ahead and add all of this? I already have 3/4 pound in there now. The SWCG book originally told me to add 0.4 lbs which didn't even register with the test kit. One more thing, there have been a couple more sets of test results in which everything was pretty much identical to these. After adding the stabilizer, the TA seemed to drop, is this normal? How much baking soda / soda ash do I need to add to raise it?

Thanks in advance for any and all help.

[BigDave]

Your TA is fine at 80, If you pH isn't moving too quickly, I wouldn't worry about it.
I would add the rest of the CYA - you're still under 30.
You might want to bump your pH a bit with a little Borax ... but maybe not, do you find that you pH rises from using your SWCG?
You don't need to worry about CH in a vinyl pool - It's strange that your test doesn't work the way it should but ... I haven't done the CH test on my water 'cause it's meaningless to me. I suppose if my water was cloudy I might check.
Regarding the brown dust (and I don't know if this would help), I had a robot cleaner for three years I ran my Intex donut - it saved me hours as my yard is tree-covered. The filterbag is pretty fine - it might help - but $300 is a good price for one. It only lasted three years but I liked it so well I bought another this year.

[rox29160]

The lady at the local pool store sold me something to reduce the ph in pools when I went to get my stabilizer, but I have never had to use it. She said I would definitely need it with a SWCG and I didn't know any better than to listen to her. My ph has been consistently around 7.2 since I put the pool up at the beginning of the summer. It never seems to change. That is why I had thought about putting in some Soda Ash to raise the PH a little since is has always been on the low side. I think soda ash also raises the Alkalinity which would knock out two birds with one stone. I just don't know how much to put in. I definitely don't want to overdo it and through the whole thing out of balance.

The instructions for the K2006 test kit says if the CH test starts out purple then there are metals in the water, hence the reason for adding the titrant before the test to tie them up. PoolDoc seemed to think my brown stuff on the bottom of my pool may have been iron so now I am wondering if this proves it. If I need to get it out, what do I use and how much of it?

[AnnaK]

Sometimes, brown gunk is just . . . brown gunk. Our pools provide a very large surface area on which dirt collects: airborne dust particles, pollens, whatever. Not all of it gets swept into the skimmer and trapped by the filter. Much of it sinks and, in due time, makes brown gunk. I dust my furniture every so often without really giving much thought to what that fine grey layer of stuff is or where it comes from. It's just dust: dander, smoke, oils, the detritus of life inside a home.

Since you haven't had an active algae outbreak and your numbers look pretty good and your water is otherwise clear you could just accept the brown gunk as part of having a pool that gets dirty. Not unsanitary. Just dirty. I have those same spots in mine and I would bet they're pretty common. I vacuum occasionally, I brush other times, I use a skimmer sock. The fine debris comes back, sometimes overnight, sometimes it takes a few days. I look at it as my pool's circadian rhythm

[rox29160]

I just didn't have any of this "brown gunk" on the bottom for about the first two months the pool was open. Then after reading on here, I started maintaining slightly higher FC levels. When I raised the FC, it was almost overnight that the gunk appeared. I had never had algae that I know of so I don't think it is algae. The water has always been sparkling clear, but the brown dusty stuff on the bottom makes the pool look nasty. Vaccuming just seems to stir it up. The pool looks spotless after vacuuming b/c you can't see the brown stuff (it mixes back in with the water) I have no way to vacuum to waste since I have a venturi type vacuum with a debris bag. It goes right through the debris bag. My filter does catch some of it before it settles back out, but no where near all of it. It will start settling again within a day. Maybe you are correct that it is just normal "stuff", it just seems odd that it seems to increase with FC levels. It sounds as though I may just have to vacuum every day to keep it stirred up. Thanks for your help Anna.

[BigDave]

Since pH is stable, I wouldn't move the TA. I would, however, move the pH up a little with Borax, 7.2 is as low as you want to go leaving little room for it to drop. We've had alot of rain recently and my pH went from the high side of 7.4 to under 7.2 in one storm ( my TA dropped as well ). The rain consumed my margin and I was still in the safe zone - had I started at 7.2... You do have room with your TA so if you want to use Soda Ash ('cause you already have it?) then, sure, just do it a little at a time ( 1/4 cup to start ) - let it mix throughly and measure the result.

The Brown Stuff: Does it really bother you? Is it staining your pool?
If it is metals, you might get more when you raise the pH - watch for that. Is there more when the FC is higher?
Perhaps your observation in the CH test is good reason to have your water tested for metals.