Algae in water on top of pool cover with holes

MikeDub

Member
Feb 22, 2021
11
Murrieta, CA
Pool Size
8403
So I recently purchased a home in December with an above-ground pool (details below). I haven't done anything to it since I moved in, except I found the pool cover and put it on it. I live in southern California (Murrieta, CA) so I didn't think winterization beyond that was necessary. So the pool cover is a solid cover with quarter size holes maybe ever 1-3 feet apart (nothing like mesh). So this pool cover got a bit of rainwater on top of it, and I assumed it would mix with the water below it through the holes. After a few days, I came out and it was absolutely covered in green sludge. The pool underneath still looks ok. A green tint but not nearly as bad as the top. I tried to siphon the top off and the amount of water on the cover didn't change, but the cover sank lower so I am pretty sure it was just exchanging water from the pool underneath to the top, and if I continue I would just siphon the entire pool or until the cover can't stretch anymore. So should I just remove the cover and risk the green goop falling through the holes into the pool? Or try to siphon the green goop specifically. Or any other options? Once the cover is off, I believe I should just treat it like any other algae-infested pool and SLAM it. Please let me know any and all thoughts, I am open to any suggestions. Thanks all and take care.

More info:
Pool Info:​
Intext 12'x24' above ground pool​
Pump: Intex SF80110-2​
Filter Medium: Sand​
Chemistry:​
I only tested it once when we first moved in well before this occurred, and it was using the little test strips that the prior home owner had. Here is those "results" but because they're strips from a first time pool owner take them with a grain of salt. I am currently in the process of waiting for a decent test kit based on the pool school.​
  • Hardness: High
  • Chlorine: Ideal
  • Free Cl: Low
  • pH: OK
  • Total Alkalinity: OK
  • Stabilizer: High
 
Last edited:

Newdude

Gold Supporter
TFP Guide
Jun 16, 2019
6,347
NY
Hey Mike and Welcome !! You have a few things working against you. The sun gets to the water above the cover and can skunk it pretty quick in Socal. The water under the cover does a little better but I suspect its too warm to inhibit algae so you're probably 0 fer 2.

How is the water filling/draining situation by you ? Some people have it better than others, I'll guess its problematic because Socal. I ask because (once proven with a reliable test kit) we will need to drain some water to lower your CYA (stabilizer) to a manageable level.

You might as well uncover the pool at this point. Its only needed to catch whatever comes down in the fall. If you SLAM Process soon, it will be an easier battle before the water gets much above 60 degrees. But you will need a reliable test kit to SLAM and the TF-100 form tftestkits.net is the way to go for that. Add the speed stir / smart stir for $30. Nobody has ever regretted it but everyone wished they bought it sooner.

While the test kit is enroute, add 4 ppm of bleach daily per PoolMath it will stop it from getting worse.

Start your education here. ABCs of Pool Water Chemistry. Lots of terms at first but its real simple once it clicks. Many of us took a few tries for it to sink in. There are many of us around to help guide you along the way, so feel fee to ask at any step.
 
Last edited:

MikeDub

Member
Feb 22, 2021
11
Murrieta, CA
Pool Size
8403
Hey thanks so much @Newdude . Yeah the weather just shifted and now were quickly moving into the 80 degree weather with no cold days in sight. I feel itll only get worse from here.

The filling/draining situation is not ideal. The closest drain is about 50 feet away. Ive been siphoning into the corner of the yard and because its so hot its been evaporating but thats with a dinky little garden hose. Not a pump with actually gpm flow happening. Itd have to sort something out to clear that distance. Filling would just be the garden hose. Hopefully its less than 20% drain and fill or im gunna have a long day ahead of me haha.

Ill order the TF-100 today then. Do you think I'd benefit from the XL version because Ill be testing chlorine a few times a day?

Thanks for the tip about adding in bleach in the meantime. Seriously appreciate it.
 

MikeDub

Member
Feb 22, 2021
11
Murrieta, CA
Pool Size
8403
Quick question for you. How do I determine 4ppm bleach using the pool math without the inital numbers? Am I just assuming chlorine starts at 0ppm and targeting 4ppm based off pool size and bleach strength?
 

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
36,202
Laughlin, NV
Pool Size
6000
Surface
Fiberglass
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-40
Your pool volume is just under 10000 gallons. So around 1/2 gallon of 10% liquid chlorine per day should be sufficient.
 

Newdude

Gold Supporter
TFP Guide
Jun 16, 2019
6,347
NY
The filling/draining situation is not ideal.
Then it’s a good thing you have high CYA based on a test strip.......... it might be fine. :)

The XL version is great for people learning to test and for those who need to SLAM. You check both boxes. You’ll mess a few tests up, Don’t get discouraged, we all did. But it’s as easy as following the directions which consists of : Fill tube to 10 ml. (That easy). Add scoop of powered (that easy) Count drops of XXX (that easy). Multiply drops by 1/2.(seriously it’s that easy).
BOOM. Accurate FC reading.
 

MikeDub

Member
Feb 22, 2021
11
Murrieta, CA
Pool Size
8403
Awesome thanks everyone. So I tried taking off the cover slowly but nearly half ended up in the pool. That's fine. Then I skimmed as much as I could. Filled the pool back up (was nearly 1.5 ft from the fill line). Started the pump. I typically didn't run the pump at all, so I'm only gunna run it for a 4-6 hours a day until my kit comes and I start the SLAM process. Then I'll run it 24/7. Anyways then I added half a gallon of chlorine. I'll continue this until kit comes.

Thank you all so much. Wish me luck!
 
  • Like
Reactions: Newdude