Mustard Algae? Dead Algae? I need help!!

Laurenc59

Member
May 16, 2021
20
Dunkirk NY
Pool Size
18000
Surface
Vinyl
Chlorine
Liquid Chlorine
I have a 28ft round above ground pool with a 1 year old Hayward pump and sand filter.
Last year toward the end of the season I started noticing a brown dusty material that was easily brushed up but very resilient to vacuuming. It always came back.
Last year was also my first year as a pool owner, I had a pool growing up but never had to take care of it myself..
After opening this year, once I got the water cleared up I noticed the same brown sediment. I read up on pool school and decided it could be mustard algae. However, my pool is in direct sun for almost the entire day. The sediment does not favor the shade or attach to walls. It seems the majority of it settles directly in the middle of the pool where stuff would settle if you created a whirl pool affect.
i have shocked the pool to 10 ppm with a CYA of 60. It seems to be holding the chlorine rather well. I have been relying on the strip tests. My Taylor test kit comes in on Wednesday.
I have also used bioguard banish, and vaccumed to waste twice but it just keeps coming back!
I am waiting for my test kit to come in to get an accurate OCLT.
I am really at my wits end here. My pool is sparkling clear but just with those pesky brown dust splotches. Nothing looks yellow to me except when I do vigorous brushing my skimmer sock does seem to catch yellow greenish hair like algae strands. Or could it be pollen?
I will upload photos of the sediment later.

Thanks everyone!
 
Welcome to the forum!
The brown dusty material sounds very like plain dead algae. Mustard algae is pretty rare.
When you get your kit, run a full suite of tests and post them here.
No more pool store potions, just liquid chlorine to add 5 ppm FC each day until you get your kit.
Did you get the K2006C - the C matters.
I suggest you read ABC's of Pool Water Chemistry.
 
I forgot to mention that the last time I added the shock level of liquid chlorine some of the brown splotches did change to a white/greyish color.

I only got the K2006 kit. Online I read that the “C” was just the commercial size of the reagent kits if I remember correctly
 
The important part of SLAM is the M - Maintain. You Maintain the FC at SLAM level by testing and adding liquid chlorine every few hours.

The C is important because it gives you the amount of FAS-DPD and CYA reagents you need. So right now you need to get refills of the R0870, R0871, and R0013.
 
Ok, they are ordered! Should be here a day after the kit arrives. I will post the full test results. Is there a link you could provide that helps with testing? Or is it relatively easy?
 
Here’s a photo, it was hard to get a good picture with the sun on the pool. The larger spots settle in the middle of the pool where there is less circulation. I can try and get a better photo later tonight.AB519451-4D42-4FF4-A7CF-28E058A6E854.jpeg
 
Here’s a photo, it was hard to get a good picture with the sun on the pool. The larger spots settle in the middle of the pool where there is less circulation. I can try and get a better photo later tonight.View attachment 334134
Welcome to the forum!
The brown dusty material sounds very like plain dead algae. Mustard algae is pretty rare.
When you get your kit, run a full suite of tests and post them here.
No more pool store potions, just liquid chlorine to add 5 ppm FC each day until you get your kit.
Did you get the K2006C - the C matters.
I suggest you read ABC's of Pool Water Chemistry.
Test results:

FC- 14ppm
CC- 1ppm
Ph- 7.4
Alkalinity-90
CH-370ppm
 

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I just added the recommended amount of chlorine. The instructions said not to test more than once per hour, when should I test again to get my baseline for the OCLT?
Welcome to the forum!
The brown dusty material sounds very like plain dead algae. Mustard algae is pretty rare.
When you get your kit, run a full suite of tests and post them here.
No more pool store potions, just liquid chlorine to add 5 ppm FC each day until you get your kit.
Did you get the K2006C - the C matters.
I suggest you read ABC's of Pool Water Chemistry.
I am keeping up with the SLAM

lost 4 ppm over night but less and less with each test today, and CC is down to 0. The brown dust has dissipated some, but not much.

just a side note- my skimmer sock has been full of yellowish stringy substance.

I noticed that yellow dusty material has been collecting on my patio furniture. Could this be pollen?
 
Yes. Pollen collects on the pool too.

Another day may be prudent. Do the OCLT again tonight.
I have kept the pool at slam levels and not failed an OCLT.
My pool is sparkling, besides the small pesky sediment spots. While there aren’t as many as before, there still are some.
I have been turning my pump off at night to try and save some energy. I brush the pool before I turn it off. And in the morning, no sediment. After about an hour of the pump running the sediment is back. What could be causing this? If I leave the pump on the sediment always resettles.
 
It may be prudent to do a deep clean of your sand filter.
 
It may be prudent to do a deep clean of your sand filter.
How do I go about cleaning it when it’s already hooked up to the pool?
 
How do I go about cleaning it when it’s already hooked up to the pool?
I do not know your pool system (a signature assists) but you would isolate the pool equipment from the pool and follow the instructions in the article.

Other option is just to move on. If you are passing multiple OCLT's, have no large FC demand each day, it is most likely a filtering issue.
 
I have typical sand filter here’s a photo. I have a 28ft round vinyl liner above ground pool. I have a Hayward 1.5 hp pump.

I understand the process I just have a few questions.
After isolating the filter from the pool do I open the drain plug on the filter and allow the water to drain before taking the multi port valve off to start the deep clean? I’m

8474D5CE-AC71-4126-B91D-2A59AE613D35.jpeg
 

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