Brown/Light Grey substance keep appearing on the bottom of my pool

[Mshepels]

Hi
I’ve been struggling with algae all last summer. I have an above ground 10,000 pool. In the end of the season I shocked the pool, vacuumed it to waste and closed it. This year when I opened the pool water was a bit cloudy but clear. I balanced PH and Alkalinity (7.5/100) and shocked the pool (2lb for 10k gallons). The next day I brushed and vacuumed and at night added another 1lb of sock. The next day I see light grey substance on the bottom that looks like what I vacuumed to waist in the end of last year after killing algae. The substance is dark light gray color and decimates when touched. I again vacuumed it to waste and shocked with 1lb at night, ran the filter and the next morning the same thing. What could it be? I know from my prior year experience is I leave it unattended for a few days algae will come back. Please help I am at a complete loss and desperate. I saw there are people with the same problem posted questions in the forum but there was no real answer. I am seriously considering draining the pool and start over.
Thank you so much.

 

[mknauss]

Welcome to the forum!
You need to follow the SLAM Process. To do that, you need a proper test kit, see Test Kits Compared. I suggest the TF-100 A proper test kit is needed to get the accurate water chemistry results needed to follow the TFP protocols.
Continue to manage your FC levels while you wait on your test kit.
I suggest you read ABC's of Pool Water Chemistry.

 

[Mshepels]

I have a very good test kit Taylor K-2006. What is the substance on the bottom and why I need a Slam Process. I looked at the Slam Process and it looks like I am in the end stage of it.

 

[mknauss]

Great. Can you post your test results?
It is very likely that is dead algae. Have you followed the SLAM Process? There are three criteria. One is crystal clear water.

The SLAM Process is not a couple of 'shocks'. It is a process that you maintain an appropriate FC level based on your CYA.

 

[Mshepels]

Great. Can you post your test results?
It is very likely that is dead algae. Have you followed the SLAM Process? There are three criteria. One is crystal clear water.

The SLAM Process is not a couple of 'shocks'. It is a process that you maintain an appropriate FC level based on your CYA.

Hello mknauss. Thank you very much for trying to help out. My water is crystal clear, see the picture I took this morning. Below are the test results.

FC 7
CC 0
PH 7.8
ALK 130
CH 260
CYA 30

 

[Holydoc]

Mshepels,

The reason you need to follow the SLAM process is that the grey residue at the bottom of your pool looks like dead algae. If that is the case, then when you have been shocking the pool, you are killing a small amount of suspended algae that is collecting at the bottom. Performing the SLAM process as described by Marty in his post will ensure that you kill ALL the algae in your pool and bring your water back to a sparkling, trouble-free state. This will accomplish a few vital things:

1. Teach you how to correctly SLAM your pool to rid it of contaminants
2. Prevent you from ever having to "drain your pool and start over"
3. Introduce you to the Trouble-free Pool (TFP) way of maintaining your pool so that this will never happen again.

Good Luck!

 

[mknauss]

Below are the test results.

Great. Lower your pH to 7.2 and then raise your FC to 12 ppm. Maintain the 12 ppm FC by testing and adding liquid chlorine at least 3-4 times per day. Brush and vac the pool surfaces daily.
When you pass the three criteria for a successful SLAM, let your FC come down to Target Range and maintain by adding chlorine daily.

Your signature shows 'salt water'. Do you have a SWCG? Can you put those details in your signature?

 

[Mshepels]

Great. Lower your pH to 7.2 and then raise your FC to 12 ppm. Maintain the 12 ppm FC by testing and adding liquid chlorine at least 3-4 times per day. Brush and vac the pool surfaces daily.
When you pass the three criteria for a successful SLAM, let your FC come down to Target Range and maintain by adding chlorine daily.

Your signature shows 'salt water'. Do you have a SWCG? Can you put those details in your signature?

A few questions:
I need to do the Slam even if the water is clear?
When you say vac the pool, you mean vac to waste?
So this staff on the bottom is dead algae, and if so how will it clear out? I've vacuumed it to waste number of times and it comes back right after I turn on the filter. Is this the new dead algae?
At this point since my CC is 0 and water is clear I only need to pass OCLT to have the process completed, correct?

Yes, I have SWCG, it is Intex, cheap but does the job. However, right now I am not using it since I keep shocking the pool.

 

[mknauss]

Your water is not clear. Brush the floor of the pool, does the pool become cloudy? Clear water means no solids (dead algae).

Your FC is just enough to kill the recurring algae. When you follow the SLAM process, you eliminate the algae. Completely.

You can vac to filter or waste. Be aware as you filter to waste, your CYA level does eventually change.

 

[Mshepels]

Your water is not clear. Brush the floor of the pool, does the pool become cloudy? Clear water means no solids (dead algae).

Your FC is just enough to kill the recurring algae. When you follow the SLAM process, you eliminate the algae. Completely.

You can vac to filter or waste. Be aware as you filter to waste, your CYA level does eventually change.

So You’re saying that filter should be picking up this dead algae. I won’t want vacuum to waist if I don’t have to. I try the process and let you know the results. Thanks so much for your help.

 

[mknauss]

Your filter will trap the dead algae. Cartridge filters are pretty good at clearing a pool.

 

[Mshepels]

So You’re saying that filter should be picking up this dead algae. I won’t want vacuum to waist if I don’t have to. I try the process and let you know the results. Thanks so much for your help.

One more question: cou

Your water is not clear. Brush the floor of the pool, does the pool become cloudy? Clear water means no solids (dead algae).

Your FC is just enough to kill the recurring algae. When you follow the SLAM process, you eliminate the algae. Completely.

You can vac to filter or waste. Be aware as you filter to waste, your CYA level does eventually change.

One more question please about lowering my PH. Could my PH be high due to higher than normal FC? It was 7.5 at some point before I added more shock. I just want to confirm that it is ok to lower my PH before raising FC to 12.

 

[mknauss]

As long as you tested pH when FC was 10 ppm or less, it is accurate.

 

[Mshepels]

As long as you tested pH when FC was 10 ppm or less, it is accurate.

BTW, I just brushed the pool and the water is still clear. I am still doing the SLAM. I put dry acid to lower the PH, will add shock tonight. Hopefully it'll do the trick. Keeping my fingers crossed.

 

[mknauss]

Sounds good.

FYI -- dry acid is Sodium BiSulfate. The Sulfate stays in the pool water. When they build up enough, they will destroy metal items. Such as your SWCG. Just be ware of that. Muriatic acid is much better to use.

 

[Holydoc]

Mshepels,

Just a reminder, when SHOCK is mentioning in this forum, it primarily means liquid chlorine or bleach, not the powdered stuff that the pool store labels as shock. When you SLAM, you:

1. (S)hock (L)evel - add liquid chlorine/bleach until your FC =12 ppm.
2. (A)nd (M)aintain - Check every couple of hours and ensure your pool FC =12 ppm. If it does not, add more bleach until the FC =12 ppm.
3. Brush and vacuum your pool at least once a day

Continue the SLAM (will probably take a couple days) until you no longer see dead algae on the bottom. Then you can do the Overnight Chlorine Loss Test and the Combined Chlorine test. This will ensure you have a beautiful and safe pool.

 

[Mshepels]

Sounds good.

FYI -- dry acid is Sodium BiSulfate. The Sulfate stays in the pool water. When they build up enough, they will destroy metal items. Such as your SWCG. Just be ware of that. Muriatic acid is much better to use.

Oh boy, too late. So I will need to get rid of them now? How, lowering the water and adding fresh?

 

[mknauss]

I would not over react on the dry acid. You are lucky in your area that you drain a bit of water at winter I imagine. But long term continued use of dry acid is not recommended.

 

[Mshepels]

I would not over react on the dry acid. You are lucky in your area that you drain a bit of water at winter I imagine. But long term continued use of dry acid is not recommended.

Got. Thank you so much for the quick responses, Marty. Have a great night.

 

[Mshepels]

Hello, I brought my FC to 12.5 ppm last night, vacuumed and brushed the pool last night. This morning there was much less dead algae on the bottom. The color of it became darker though almost black. I vacuumed, brushed, cleaned the cartridge. FC is 12 now. The pump is working for a couple of hours now and there is even less dead algae. The pool is crystal clear. I am cautiously optimistic. It might just work.