Diatomaceous Earth catalyst for Yellow Algae?

[Macysumo]

Had a long bout with Mustard Algae two weeks ago and finally got it licked but it came back today. Seems it always shows up after a big rain like we had this morning but I added ~6 cups (3.5 lbs) of diatomaceous earth into my sand filter today too and am wondering if that could have poked the MA beast in my filter?

Raised FC to 28 according to my pool math app and cya of 70. I did let the FC get to 3.5 ppm for overnight a couple of days ago...maybe that is too low but the MA didn’t show up until I ran the pump on high for a couple of hours after applying the DE.

if this SLAM doesn’t work I’ll go back to the 50ppm SLAM that rid the MA before.

Should I flush/backwash the DE after the SLAM?

 

[HermanTX]

I always backwash after cleaning up algae. I have a DE filter and it always sticks to it so just need to get rid of it to waste via backwash.

 

[Macysumo]

Still fighting this Mustard Algae beast daily since Aug 8. when I "accidently" let the FC get to 3.5. Maybe the MA is localized in the filter because I can't seem to eradicate it after cleaning everywhere else. Cleaned every source I could find, still there every stinking day.

CYA way down... last test was 40, probably lower now that I've vacuumed to waste several times and refilled since. FC still at 24 ppm tonight...testing twice or three times daily and average over last five days is almost 27ppm!

I've put more chlorine in this pool than you can imagine this month. Costing me a fortune in water and Bleach...ugh! 8.5 Gallons and 22 lbs of 73% Cal-Hypo (+207 ppm) in August and I still can't get the yellow mustard to die. Done SLAM after SLAM after SLAM then Mustard SLAM with little effect.

I've been running the pump in the recirc. mode over the last 48 hours and vacuuming to waste then refilling at least twice a day thinking I can at least eliminate the filter as a variable. I'm hoping I don't see any tomorrow but this is getting extremely frustrating.

 

[Macysumo]

Pump in recirc did the trick clearing up the yellow algae. Mustard Algae seems to be gone (or hiding)!

Tried cleaning the old sand (6 yrs since new filter) and after two hours gave up. It just wouldn't clear up and had a layer of yellowish shiny stuff on the top that wouldn't come off, even after scraping that layer out... it kept coming back.

Disassembled the filter and vacuumed out the old sand and replaced with 300 lbs. of new Quikcrete Pool Sand (#20). Old sand to go on the yard (hopefully the MA won't visit again from that mess).
Filter is back together, followed Sta-rite Crystal Flo startup procedure, backwashed and rinsed. Waiting for pool to refil.

Took complete readings Saturday (48hr ago) before shutting down the pump and filter:
FC 14.0
CC1.5
pH 7.5
TA 40
CH 300
CYA 24

Added two quarts of 12% bleach last night and got in the pool to agitate it while no pump.
Just another day in the battle...fingers crossed this helps. I'm not putting any DE in this sand for the time being. I'm convinced it had something to do with the MA return. Maybe I'll try again after a few weeks of no algae.

 

[duraleigh]

Algae is simply not related to filtering. You get algae through inadequate levels of chlorine. Filtering cleans dirt, dead algae, debris from your pool water but it has no important effect on the creation or elimination of live algae...........If you have algae in your pool and would like to remove it, chlorine is the answer