Whenever I run my Hayward Sand Filter I get what looks like dirt in all the little crevices of the bottom of the pool liner. If I clean the pool spotless, it doesn't return till I run the pump again. The water itself is crystal clear, blue. I've acquired the pool with the purchase of the house 5 years ago, and had this problem from the beginning. Not knowing a thing about pools, I mainly thought it was the filter. So, I changed the sand probably 3 times, put in new laterals - thinking they might be cracked, replaced the top lid gasket. Still no luck. I've backwashed, vacuumed to waste, thou not all the time. Now I'm thinking maybe algae. I put a white stocking over the return, I got some white sand, nothing else. But when I did this I hardly got any dirt at the bottom of pool. My pool is 21 feet round. Have a Hayward Sand filter S166t with a 1.5 Speck pump. I've heard the wrong size pump if too strong can cause dirt to return, but all the stores tell me this pump size is fine. I tested the water with the pool store and it comes up great. No issues. One strange thing, I was low on water, after cleaning pool spotless, ran the garden hose for about 2 hours, and noticed some of the dirt was returning to the bottom of the pool.. I was not running the filter!! Then I thought maybe the dirt is coming up from the liner, holes, tears. I found one, 1/2" and patched it. But all the experts tell me dirt will not come up that way, and I would be losing water, which I am not. So back to the filter, garden hose ? Seems like the motion and current is causing dirt ; algae to appear? I'm willing to buy a new filter if that would solve it. The dirt or algae is brown, turns to dust when moved, sometimes leaves a yellowish mark, that eventually goes away. Any ideas, advice , comments, would appreciate!!!
Mustard Algae?
- Thread starter SusanR
- Start date
Welcome to TFP!!!What test kit are you using?
Specifically, what is your CYA and what FC are you maintaining?
Saying the water "comes up great" does not tell us anything. We want specific numbers from one of the recommended test kits: Test Kits Compared
I take the water to be tested at Leslie Pools in my area. They do it all for me. And, the results have been coming up fine, according to their test.
Yeah ... we don't trust pool store testing around here.
If you would like to take control of your pool, we can certainly help you learn a better, cheaper way than trusting a company that has a vested interest in selling you something.
So, at this point, impossible to know what you are seeing on the bottom of the pool. I would guess that your FC is too low for your CYA (see the FC/CYA Levels) and that you have a low level algae bloom.
Check out Pool School, starting with ABCs of Pool Water Chemistry if you are interested in taking control.
If you would like to take control of your pool, we can certainly help you learn a better, cheaper way than trusting a company that has a vested interest in selling you something.
So, at this point, impossible to know what you are seeing on the bottom of the pool. I would guess that your FC is too low for your CYA (see the FC/CYA Levels) and that you have a low level algae bloom.
Check out Pool School, starting with ABCs of Pool Water Chemistry if you are interested in taking control.
Oly
Gold Supporter
What Jason said. 
Learn about pool water chemistry and how to accurately and repeatably test your own water.
Don't add anything to your pool unless you know exactly how it will affect your water and your pool system.
Welcome to TFP. This place is the answer for pool / spa owners.
Learn about pool water chemistry and how to accurately and repeatably test your own water.
Don't add anything to your pool unless you know exactly how it will affect your water and your pool system.
Welcome to TFP. This place is the answer for pool / spa owners.
We've had the same issue since we opened our pool in May. Crystal clear water but clumps of fine brown silt in center of pool floor that would disappear into a cloud when you touched it. At first it was just a few clumps of brown sediment but eventually it wound up being quite a bit. Noticed that if we left the pump off the brown sediment would not appear. Saw on another board that someone discovered they didn't have enough sand in their filter or that the sand needed changing. We opened the sand filter and it was completely clogged with hard clumps of sand and dirty water (this was new sand that we put in the filter in May-we also cleaned the entire inside of filter in May before opening the pool). Dumped the sand, cleaned the inside, the laterals, etc and refilled with new sand from the pool store until it was just over 3/4 full of sand. It was probably only 1/2 full with sand prior to this. Restarted the pump and woke up with a crystal clear pool for the first time since May. It's worth a shot before you start putting a lot of chemicals in the pool. We are on day 3 of a perfectly clear pool each morning. It seems we didn't have enough sand in our Hayward sand filter.
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