Brown powdery sediment on pool floor

[Writchey]

I purchased my house and settled escrow a month ago. The pool looked ok when I made my offer in April. Now I am experiencing problems with algae which I counter with algaecide and chlorine (but there seems to be a controversy whether chlorine combats algae). I am starting to see a fine powdery brown sediment on the pool bottom which actually etches a pattern where it collects. If I vacuum the pool to the sand filter the sediment reappears by the next day.

One bit of advice I received is to vacuum the pool to waste, but I discovered the PVC valves on the output side of the sand filter are frozen so that is ruled out until I can have them replaced. A further piece of the puzzle relates to a problem I had with the multiport valve. To cure a leak from this valve I replaced the o-ring, but when I reassembled the valve, I got it wrong. In my haste to fix the problem I tried different ways of assembling the valve. Finally I got wise and called an expert who was able to give me clear instructions on how the multiport valve goes together.

A person in a pool supply store told me that I probably disturbed calcium buildup in the sand and this is what I now observe on the bottom of the pool. There is no grit to this sediment so it is not sand. If it was gritty that would indicate broken laterals.

I called to inquire about replacing the PVC valves and decided to hold off on that for now. I have had a lot of expenses associated with my move.

Any advice is appreciated.

[kaptn]

I pretty much have the same thing and swear its mustard/yellow algae. It grows but when you brush it then it will be suspended in the water like a fine dust cloud.
The only reason I say it is an algae bloom is that one time when it was evident on the floor of the pool I walked around the edges and dispersed some granular shock and the next morning you can see on the bottom of the pool the ring around the edges where the shock had landed. Have you tested your Free Chlorine level? When I have this stuff there is like no chlorine at all in the pool.

[Writchey]

Yes I tested low so I have been shocking the pool. The water is crystal clear. It is just the sediment that is a problem. I am going to start backwashing and filtering to waste. See what that does. Some of the advice I get from reading web articles are convincing me that I have been too timid about backwashing.

[Writchey]

Update on sediment issue.
For the last two days I have vacuumed to waste, then backwashed and rinsed. I also brushed the pool shallow end and part of the deep end. Green algae is building up. Pool temperature is 80 degrees today.

My Chlorine level is low so I will throw in some shock tonight and also some algaecide. After getting the electric bill for July (over $400) I am letting the filter run fewer hours. Now 5 hours instead of 8.

[Writchey]

Yes I tested low so I have been shocking the pool. The water is crystal clear. It is just the sediment that is a problem. I am going to start backwashing and filtering to waste. See what that does. Some of the advice I get from reading web articles are convincing me that I have been too timid about backwashing.

I meant vacuuming to waste and backwashing.

[kaptn]

any update on this weekend?

last week I shocked my pool with bleach 6%...put in about 8 galloons worth and this brought my Free Chlorine up to about 26.0...it dropped down to about 21.0 and the next night put in another 2 galloons to raise it back up.

I let it drop back down and it seems to be looking pretty good so far. Prior to this shocking off it I had used a bottle of sea-klear algae remover with 2 lbs of granular calcuim shock. I dont think that did anything because the next day or two it still was showing the sediment.

But after that shock of bleach its been ok so far. I will monitor it this week. I also backed off the backwashing wondering if that has anything to do with it. I did run the filter pump for about 2 days after bleaching it.

[Writchey]

As I study this more I learn that a sand filter will not filter out dead algae. I have been trying to vacuum to waste (at least four times on different days) but that takes a lot of water. After vacuuming to waste I was then backwashing and rinsing. Water in the site glass was coming clear after about a minute running the process.

The situation seemed to be getting better. I also upped the amount of Leslie's algaecide and Walmart's Shock and Swim quite dramatically. Last Sunday I spent at least one hour scrubbing the pool with various brushes. No matter how hard I brushed there were some spots left on the pool bottom, which eventually went away, presumably due to heavy chlorine and algaecide I poured in after vacuuming.

Results? Now I have a slightly green colored powdery sediment. The amount and distribution are perhaps a little less. After adding the chemicals the water turned green for a few days, but now it is clearer.

The algaecide directions say to remove the dead algae. Ok, but now I think I am learning that a sand filter like mine is incapable of removing dead algae. How then do you get rid of this stuff besides sending it to the waste line?

[floridapooltech]

As I study this more I learn that a sand filter will not filter out dead algae. I have been trying to vacuum to waste (at least four times on different days) but that takes a lot of water. After vacuuming to waste I was then backwashing and rinsing. Water in the site glass was coming clear after about a minute running the process.

The situation seemed to be getting better. I also upped the amount of Leslie's algaecide and Walmart's Shock and Swim quite dramatically. Last Sunday I spent at least one hour scrubbing the pool with various brushes. No matter how hard I brushed there were some spots left on the pool bottom, which eventually went away, presumably due to heavy chlorine and algaecide I poured in after vacuuming.

Results? Now I have a slightly green colored powdery sediment. The amount and distribution are perhaps a little less. After adding the chemicals the water turned green for a few days, but now it is clearer.

The algaecide directions say to remove the dead algae. Ok, but now I think I am learning that a sand filter like mine is incapable of removing dead algae. How then do you get rid of this stuff besides sending it to the waste line?

You can increase the filtering capability of your sand filter by adding a scoop of D.E. into your skimmer with the filter cycle running. It would be recommended that you start getting your algaecide from a real pool store as the Walmart pool supply line is inferior compared to the other (much lower algaecide content). Also, shock from most pool stores and Walmart especially has a high pH content is they use di-chlor. The correct type of shock you should be using is calcium hypochlorite which is almost pH neutral and much better quality. Most stores don't carry the better shock due to the fire system they have to have in the store. Regarding sediment returning back into your pool, have you checked the lateral's in the sand filter to make sure they aren't broken? This very well may be your problem!

[Writchey]

Thanks for the tips. I have not checked the laterals, because this would mean emptying out the sand, would it not? I have felt samples of the sediment, and can not detect any grit, whatsoever. The sediment disperses in a cloud if you run a brush over it. This is why I describe it as powdery.

Another aspect of this, I do not understand, is that where sediment is deposited in places, the vacuum will pick it up ,but where it was is there are spots like the pool surface has been etched. These spots are more or less black and to get them off I have to brush over them vigorously.

Also, I am discovering some of the tile grout around the pool has a black growth that is hard to scrub off. Many of the pool fittings also have this black growth. Is this black algae?

With heavier doses of shock and algaecide the situation seems to be getting better. But I think I am learning that once algae gets in your pool you relaxing days are over. I wanted something that would keep me more active. It seems I got my wish. Brushing and vacuuming are now the way I start my days.

[floridapooltech]

Thanks for the tips. I have not checked the laterals, because this would mean emptying out the sand, would it not? I have felt samples of the sediment, and can not detect any grit, whatsoever. The sediment disperses in a cloud if you run a brush over it. This is why I describe it as powdery.

Another aspect of this, I do not understand, is that where sediment is deposited in places, the vacuum will pick it up ,but where it was is there are spots like the pool surface has been etched. These spots are more or less black and to get them off I have to brush over them vigorously.

Also, I am discovering some of the tile grout around the pool has a black growth that is hard to scrub off. Many of the pool fittings also have this black growth. Is this black algae?

With heavier doses of shock and algaecide the situation seems to be getting better. But I think I am learning that once algae gets in your pool you relaxing days are over. I wanted something that would keep me more active. It seems I got my wish. Brushing and vacuuming are now the way I start my days.

Your algae outbreak isn't a permanent issue and once completely treated, it will not re-occur as long as proper CYA, CL and filtration is met. This black substance you are explaining sounds like black algae, which can be described as slimy algae if you are to touch it. It is not harmful, however, over time will destroy your pool surface as it "roots" instead of acting as a surface algae such as the others. To remove the black algae, you will need to bring your chlorine level up to super-chlorination/shock levels and hold them overnight. Also, you will want to get a good "blackout 90" algaecide, disperse it directly over the algae and not disturb it overnight (pump off). Before any of this is done, the algae spots needs to be scrubbed with a hard metal bristle brush to scrape off the protective "slimy/dead" layer. If you are dumping large amounts of chlorine into your pool and noticing a free chlorine level is not increasing, or it's effectiveness is just not right, you may have a CYA level which is too high. The effective level of CYA should be 30-50 ppm (30-100 ppm is acceptable). This can be overcome also by reaching what is called "breakpoint chlorination". Again, regarding the laterals, yes, unfortunately you will have to remove all the sand which can be tedious. Once the sand is removed, inspect all the laterals especially underneath where you may not think to look as they may be cracked or broken. Also, when was the last time you changed the sand? It is possible the effectiveness is now depleted. I hope this information works for you and can help remove the sour feeling of owning a pool (which is meant to be pleasurable). If at all you need any further technical assistance, please feel free to contact our service department toll free. Also, we regularly answer questions on this forum!

[Writchey]

Also, when was the last time you changed the sand? It is possible the effectiveness is now depleted.

I just moved into this property in June and have no way of knowing the history of the pool. When we made an offer for the property back in May the pool was clean and clear.

During the home inspection we ordered, the inspector noted the multiport valve was leaking so when escrow closed I went about cleaning up all the little things his inspection uncovered. I determined the leaking multiport probably needed a new O-ring so I replaced that, but unfortunately got the valve stem put back together wrong and the timer ran the pump when the valve stem was incorrectly positioned. Eventually through the help of a local pool supply house I assembled it correctly, but I don't know what effect letting the system run with the mis-aligned multiport might have had. Perhaps this could have damaged the laterals? If there is a serious probability misalignment could cause damage, you would think the design would incorporate a keying system to prevent botched alignments. Even something as simple as a heavy scribe mark would help.

If I cannot clean this up using the course I am on (shocking, scrubbing, and algaeside) I probably have no recourse except to look hard at the option of replacing the sand. How much would you estimate it should cost to have an expert accomplish this?

I want to emphasize that the sediment has changed color and decreased as I worked on getting rid of the green algae. The sediment is now definitely green colored, which strengthens my conviction that the filter is simply not removing what I vacuum. A pool supply store here recommended a sand rejuvenation treatment so I bought a bottle, but am waiting to gather more evidence before using it.

Will floculent help this issue? That, and Pool Bright were other suggestions to try.

[floridapooltech]

ok. "sand rejuvenation" is just another chemical the pool store sold you to get money. Sand usually lasts about 5-8 years before it needs to be replaced. The laterals are most likely your problem as they are what seperates the sand from returning to the pool. The botched installation of the spider gasket is not going to cause any damage inside your filter, if anything, it would only cause a leaky mess! You may not have even damaged the gasket if you caught it fairly quickly. Make sure when everything is fixed, you don't backwash the filter too often as a dirty sand filter will always clean better than a clean one. Replacement sand is going to cost quite a bit as your putting in somewhere around 200 lbs. most likely. Like I said it most likely the laterals, not the sand. Also, don't let the pool store con you into buying a bunch of chemicals which will not "cure" the problem, but temporarily fix it. If you can, perform a full panel test and post the results on here along with photo's of the algae. I'm very curious to see what your CYA and pH/alkalinity levels are at since this will have a huge impact on your FC or effective sanitation. In the mean time, don't put the flocculant, algaecide, pool bright, or rejuvenation kit and whatever else they are guessing and having you buy in until we see the results!

The results should contain:

FC
TC
pH
TA
CYA
CH
TDS
PHOS
NITR

[danswthwolvs]

First make sure all leaves & sticks are out of pool so that what u have remaining is the brown sediment or algae.
The filter will not get rid of this by itself..... so no amount of "waste", "backwash, or "rinse" will help - your just doing a lot of water in!!! and going round in a (vicious circle)
When algae settles on floor of pool Go to skimmer box and clean out then line and 'NO' not with a"stocking" - not fine enough, but thin WETTEX or CLEAN RAG. must be finer than stocking.
Then put skimmer box vacuum head in place & vacuum keeping eye on suction & pressure
After short vacuum turn off and clean Skimmer box liners in bucket of water. You may have to repeat this only once or twice.
'Pool Inlet Pipe' & 'Skimmer Box Vacuum Head 'could also have a homemade vacuum bag, pehaps pump strainer basket could have a dense stocking place inside. GOOD LUCK