Brown gunk on the bottom of pool

[rox29160]

I have an above ground pool with a saltwater chlorine generator. The ph and chlorine levels have always been really easy to maintain with this system. I think I still may have some type of algae though. It is this brown "stuff" on the bottom. After you vacuum it up, it takes about 3-4 days before it starts reappearing. I have even "hyper" chlorinated a few times just to see if that would make a difference. It has not done anything, other than give me a bright yellow solution with my test kit for a few days, lol. Any ideas on what it could be or how to get rid of it? Oh yeah, if you leave it in there for more than a day or two, it gets harder to remove. It almost acts like it stains the liner.

[Watermom]

Hi and welcome! Can you tell us what kind of pool you have, what kind of filter you have and size of pump. Also, we need a current set of test results taken with a drops-based kit. We will also need to know exactly what all you have put in your pool meaning ingredients, not just product names or "shock."

Sounds like you are using an OTO kit. You really need a better kit. The one we recommend is the Taylor K-2006 or 2006C (same kit, larger bottle of some reagents). If you buy it through the Amazon link in my signature, the Pool Forum makes a little money on the sale which helps us keep this form online. Only buy if the seller is Amato Industries, however. Some other sellers are substituting the K-2005 which you do NOT want. If Amato isn't listed, wait a day or two and try again. They seem to restock pretty quickly when they sell out.

Repost with requested info and somebody here will try and help you.

[PoolDoc]

Hi Rox;

I just move your thread where you can post -- sorry, but I upgraded your user status, without moving the post.

Regarding the brown stuff, it could be algae, or it could be iron from your fill water. Do this:

#1 - Tell us what your chlorine levels are -- day to day -- using your OTO / phenol red test kit.
#2 - Test your stabilizer level, or get it tested and tell us what it is.
#3 - Assuming that your pool was filled with the same water that goes into the toilet, check the inside of your toilet tank. If it's dark brown, you have iron. If it's not, I need to know if you have a water softener on your water line.

[rox29160]

Thanks for responding Watermom and PoolDoc! Sorry it took me so long to reply back. I couldn't find my original post when searching for it.

Watermom: I have a Intex Ultra 16' x 48" above ground, (5,061 gallons). It has the round accordian paper type "A" filter. I don't know what these are called. The pump is 1,500 gph (per Target's website), also by Intex. The SWCG is Intex Krystal Clear. All I have added to the pool is about 125 lbs of salt and 1/2 lb of cyuranic acid. I did add a gallon of bleach to it while I was filling it up to keep it from getting nasty before the water got up to the inlet of the pump. Since then I have not added anything. You are correct, I have only been using a OTO kit. I have been debating on whether to buy one of the Taylor kits. I am wondering if something other than my chlorine level may be the culprit. Amato is evidently out of the K-2006 kits today, I will check back the end of the week.

PoolDoc: I filled the water from a well so iron could be a possibility. I will test the water tonight and re-post. I do know that the inside of the tank is brown. It is not as bad as some other toilets as I have seen, but it is brown. I started having toilet trouble while I was filling up the pool so I remember very well what it looks like. I don't have a water softener installed. Is there somthing that can be added to the pool water to remove or treat it for the iron?

Thanks again for your help.

[rox29160]

I tested my pool water with the OTO kit I have when I got home from work. The chlorine level is somewhere in the 1.0-1.5 ppm range, which is where it usually is unless it has recently rained. The ph is a little lower than my kit says is ideal, but only by a little. I would say it is around 7.5. The kit says ideal is 7.6. It is hard for me to match up the colors exactly which is why I was already contemplating buying one of the Taylor kits before Watermom suggested it to me in the previous post. The chlorine and ph levels are pretty consistent. It doesn't matter if I test in the morning or in the evening like I did tonight. I don't seem to be losing much chlorine. I only run my SWCG for 2 hours per day. Any more than that and my chlorine readings get up around 5 ppm.

I double checked the tank on my toilet. The "brown" I referred to earlier is a brown ring around the top, at the normal water level, not the entire inside of the tank (if this makes a difference).

I also got in the pool tonight and investigated the brown "gunk" a little. The walls of the pool are NOT slimy at all. I have read that this is an indicator of algae in other threads. The brown stuff looks kind of like dirt, but when you try to pick it up with your fingers, it disintegrates. It is slimy almost like the slimy mud in the bottom of a river. I don't have a lot of it. It is just in small isolated spots on the bottom of the pool about the size of quarters. I tried vacuuming it up, but I have the cheap vacuum that came with the pool. (the kind that connects to the garden hose and then catches debris in a little net) After tonight, I am sure that once the "gunk" is disturbed, it just washes right through the holes in the net.

Any help is appreciated. Thanks in advance.

[PoolDoc]

Could be dead algae -- have you had algae?

[BigDave]

I had better luck vacuuming finer particles with the Intex venturi-vac by adding a nylon stocking inside the filterbag. I cut the foot and leg 3 - 4 times longer than the filterbag, stuffed it in, and secured the open end of the stocking over the venturi-vac outlet with the filterbag drawstring.

[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.

[rox29160]

Thanks for the reply BigDave. I will pick up some Borax. I've been waiting all summer for my PH to go up like the pool store lady told me it would, instead of buying something else. I knew I was on the low side. We have had a lot of rain as well, which may be the reason my TA dropped from 90 to 80 and also the reason my PH has not been increasing. I do not already have Soda Ash so it doesn't matter to me which one. I just thought my TA needed to be bumped up slightly too and Soda Ash would do both. I'll stick with Borax per your recommendation.

The brown stuff is just a nuisance. It comes back every day after vacuuming. The water is clear but the brown stuff settles out to the bottom and makes my pool look dirty. Before anybody comes over, I have to hurry and go vaccum the pool.

[BigDave]

I supppose it's personal preference for me. I increase TA with Baking Soda and increase pH with Borax; seems to me it's more targeted - just my thinking, either way will work. BTW, it will take twice as much (by weight) Borax as Washing Soda to have the same effect on pH.
Swamp Mistress ( http://www.poolforum.com/pf2/showthread.php?10124-First-pool-might-be-our-LAST...name-says-it-all!/page6 ) seems to have had luck with a series of improvised filters.

[AnnaK]

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.

Each pool is unique and who knows why that brown stuff invades. You've reported clear and sparkling water and no CCs to speak of. Your pH is a smidge low but that's personal preference. It's 'in range' at any rate.

I know those patches of brown are unsightly and it is frustrating that they come back after vacuuming and/or brushing. In my pool, it only happens during late July/early August. When it's just us here at home, I toss the dogs in to stir things up. When we expect company I might vacuum to make it all look pretty but, more then likely, I'll just let the dogs swim for a while and scoop out the fur before the guests arrive.

Does the bottom of the pool feel squeaky clean? Not slimy? That's one of my hallmarks: a slimy feeling bottom heralds biological invaders and I might dump some extra chlorine in, regardless of what the test says. If the bottom feels clean then I'm going with Occam's Razor: sometimes, a kiss is just a kiss . . . and brown gunk is just part of the pool's life.

[rox29160]

Dave: Thanks, I had actually read somthing similar to that before about using batting and tube socks. I haven't actually tried it yet. I haven't figured out in my mind how to attach it to my vacuum so it works effieciently yet so I haven't tried it yet. I might just tie it on tonight and give it a go and see what it does.

Anna: Every thing has always felt squeaky clean. Mine did show up in late July so maybe it was a coincidence that it was right after I raised my FC levels.

[rox29160]

I made and improvised filter out of four old socks to use in combination with my venturi vacuum and debris bag. I simply put the socks, one inside the other, and tied them around the outside of the debris bag. I vacuumed all the brown stuff up a week ago and it still has not returned. (Previously, it had been coming right back after vacuuming. Most of the time within 12 hours.) The sock on the inside, the first filter if you will, was almost completely brown after vacuuming. The socks got cleaner and cleaner as you worked your way out.

I have added 3 cups of Borax so far and let it mix in for a couple of days each time. It has changed my ph from 7.2 to maybe 7.3. I added another cup or so over the weekend and plan on checking it tonight to see where my ph is now. It seems like I am having to add an awful lot. The Pool Calculator said I only needed like 11 fl oz to raise it to 7.5. I am now at around 16 fl oz. Twelve ounces hardly made it change at all. Maybe I did something wrong on the calculator. Anybody know how much I should have to add?

[BigDave]

Did you get alot of rain while you were trying to raise the pH? Irene maybe? My pH went from 7.5 to 7.2 in Sunday's storm. If it was the storm, yout TA probably dropped too, not that you should adjust it, just what acid does to a pool.

[rox29160]

I didn't get hardly any rain from Irene, but I got about 1-1/2" Monday after she was long gone, which will probably make my PH and TA worse. I had checked the PH before Irene was supposed to hit just to beat the storm. I've been dissolving the Borax in a bucket of water and then dumping it in the pool, so I don't think it is settling to the bottom or anything.

[Watermom]

You don't need to pre-dissolve the Borax. Just pour it slowly into the skimmer breaking up any clumps.