Yellow/Brown dusty deposits that reappear repeatedly

[matt4x4]

Ok, I found some algae with similar if not identical properties - called Brown Algae or Silica Algae - caused commonly through excess silicates and nitrates, inadequate light (like covering your pool because you're not using it much due to cooler weather).
Fed by things such as fertilizer - hmmm - fall, farmers fertilizing the fields before turning them over, me, living in the country? Anybody else in the country?

Anyways, that's all i have right now!

[Rangeball]

I live in a small town surrounded by country

Of course all our fertilizing was done in the spring, fields still have standing corn and beans. I don't cover my pool, but I don't know where silicates or nitrates would come from, have only used bleach. Having owned a pool for 12 years, this is the first year I noticed this stuff, and is also the first year I added salt. Coincidence? Perhaps the silicates are in the salt?

[jstonemo]

I don't live in the country, but close to it. I am in the KC suburbs on the edge of country land. My pool is not covered either. I have my FC over 20 right now and I am watching it. Gonna have to buy some floc and DE tonight.

[raptureready1953]

Hi

I have been posting on another part of the forum. I have the same stuff. Mine started in July, really right after I put the pool up. I just thought it was dust/dirt from trees, and dirt/clay rd. I have been fighting this mess for awhile. Chlorine is above 25 for at least three days. Did dump 1/4 of water this morn and refilled. Been sweeping/vacumming. ETC. I do not have a way to backwash/ have a vinyl pool with the pump that came with it. I do have a new filter in it. Ok, it was like mentioned until I left to help dd with new baby. DH forgot to keep the chlorine up ..well when I came back it was dark green thru the whole pool. My pool today is a pretty blue with cloudy substance but notice the brown gunk when I sweep. Just like described. Ok, keep chlorine up but what happens when I let it drop back to swimming level, will that brown stuff come back? I havent got rid of it yet either. I do not cover it, I do live in the country, and my bro in law has his in full sun and he has it too. He does not cover his either. (lives next door) I havent been able to swim in the last two wks. I really would love to use the pool before cool weather sets in here in NW Fl panhandle. Thanks for any help. Oh, what is FLOC? And where do I get it? Thanks.

[jstonemo]

Floc is flocculant. It is a product that you add to the water that allows really fine particles to stick together into larger particles that your filter can catch and remove from the water. You can get it a your local pool store.

[Rangeball]

I was unable to get a sample of the stuff. It vaccuums up very easily, and doesn't act like any algae I've ever seen, but I do suspect it's some form of algae.

Wierd, my CL levels and use rates haven't changed, I'm still getting the same readings. My PH has crept up to over 8, so I need to knock it back down to increase my CL effectiveness. Perhaps that's why it was able to get started.

We've also had almost zero swimming activity in the pool for the past two weeks, which is never good for ultimate circulation.

[jstonemo]

Well, I had the CL levels at 23 ppm overnight last night and I added Alum to the filter to act as a filter aid. I woke up this morning and checked the pool. It is almost totally clear and clean. The CL level dropped to 19.5 ppm overnight, so something was being metabolized. In fact, after adding the bleach last night to get the levels above 20 ppm, I was in the yard and could smell the chlorine smell half way across the yard.

I don't think that adding 6.5 gallons of bleach to 12,700 gallons of water would make it smell so strongly. I am assuming it was chloramines from something breaking down. I can hardly smell anything this morning and the CL is still high at 19.5 ppm. I am going to try to keep it up near 20 for the rest of the day just to make sure everything is dead.

[Rangeball]

Had you vaccummed the pool before you shocked? If not did the "stuff" change color post shock?

[chem geek]

Well, I had the CL levels at 23 ppm overnight last night and I added Alum to the filter to act as a filter aid. I woke up this morning and checked the pool. It is almost totally clear and clean. The CL level dropped to 19.5 ppm overnight, so something was being metabolized. In fact, after adding the bleach last night to get the levels above 20 ppm, I was in the yard and could smell the chlorine smell half way across the yard.

Man, this stuff is incredibly hearty. You had earlier quoted a CYA level less than 30 since it was getting cloudy at 30 (you said maybe 25, but it could be even lower than that). An FC of 20 with a CYA of 20 is a disinfecting chlorine (HOCl) level of 2.1 while at a CYA of 30 it is 0.9 so this is well above Ben's shock levels in his table and is higher than my own guess at 0.5 being sufficient to kill algae. It would seem that the easier-to-kill green algae seems to get killed over about a week at disinfecting chlorine levels of around 0.2-0.3 (so 0.5 would be faster), but this brown stuff needs somewhere between 1-2 ppm of disinfecting chlorine to kill. Yikes! Those people with high CYA in their pools are going to have a heck of a time killing this stuff. At 70 ppm CYA, it might take 46-58 ppm FC to kill this stuff.

As for the chlorine smell, yes you probably were smelling chloramines as intermediate by-products since these are formed rapidly. Then they are more slowly broken down (releasing nitrogen gas) and the smell goes away. This just shows that this brown stuff contains either ammonia or nitrogenous organics.

Richard

[tootic]

I'm having the same problem with my ag pool. It started about 2 weeks ago. I got in to vacuum as cold as the water is this time of year and after I ran the filter for about 2 hours, I saw the same brown algae-like substance on the bottom but mostly in the middle area. My water is also a cloudy blue after vacuuming. I'm going to try doing a super shock but would like to know how much de to add to my sand filter. This stuff definitely seems to be blowing back in. When I backwash after vacuuming, there is only clear water coming through the hose. I'm also going to try using a filter saver (nylon skimmer sock purchased from In The Swim catalogue). Hopefully, if I vacuum with this sock in place, it will catch some of that dam BROWN STUFF. I've had an ag pool for the past 15 years with no problems but the past 2 years have been a nightmare. I didn't know that you could add de to a sand filter.