Battling small amount of algae

[KJB1]

I have been having this problem for a month or so. I get small patches of algae on the walls once in a while. Today it has been hot with the solar cover on and when I took it off I had a couple spots. One on the shallow wall by the sun shelf and some on the wall by the shallow spa step. All test results are good,free chlorine is actually high at 9.0, cc 0, cya 40, ph 7.6. I brush pretty often 3-4x a week probably. My last ONCL test was last week and .5ppm
Could it be lack of pump run time? I run it for 2hr at 2200rpm and 6hr at 1100rpm. I also run it when I am going to swim.

This is making me crazy, I don’t know how algae can show up with 9ppm FC, but I am also new at this.

 

[mknauss]

Do you test the FC after brushing?

Last time you tested the CYA?

 

[KJB1]

I just tested today after brushing and the filter running about 20-30min. That’s when I got FC 9ppm and CYA 40. Tested CYA about 5 times to make sure it was 40. Started to disappear at 50 but could still see it.

 

[mknauss]

Great. Checked the Poolmath logs and could not see the last time it was checked.

Only thing I can say is brush. Brushing and swimming helps mix things up. I suspect long periods stagnant (low pump run times) and covered creates spot issues.

 

[KJB1]

I am thinking the same thing. It is in areas sort of off to the side of return Jets and it has been 100 degrees so the shallow water must be pretty hot. I’ll up the pump times some until the heat passes. So it is possible for algae to grow even with correct levels with poor circulation/covered? Good to know, I am still learning, this is my first summer. I did miss the CYA when I saved the test results. Thanks.

 

[mknauss]

Intense UV/heat can consume isolated /shallow areas of FC. If you brush the pool often enough those small spots will disappear quickly with the chlorinated water pushed into those areas.

 

[KJB1]

Intense UV/heat can consume isolated /shallow areas of FC. If you brush the pool often enough those small spots will disappear quickly with the chlorinated water pushed into those areas.

They do disappear instantly with a quick brushing. Even my hand can remove it easily. I just sort of panic at the first sight of any issues with a new pool. I’ll just have to step up my brushing. The worst of the heat for the year will be over soon too. Earlier in the summer I didn’t have this problem. We probably were swimming more often though.

 

[KJB1]

ugh. I think I’m ditching the cover. Checked my test and all were pretty much perfect. Put the cover on for 2 days and little patches of algae again. This time, a couple small spots on the wall, corner of a step and some even above the waterline on the tile. Very odd. Comes off immediately with brushing. ONCLT done last weekend and almost didn’t even register (less than .5).
I’m thinking it maybe could use a SLAM just for good measure? Water couldn’t be any clearer. Those spots after covering are giving me anxiety after reading about Mustard algae.

 

[KJB1]

asked the full time commercial pool cleaner where I work. He said raise the CYA to 70, lower chlorine and increase pump time/speed. I just said thanks and didn’t argue. I don’t understand how they keep pools clean like that.

 

[wireform]

KJ
You haven't filled in your signature with what equipment and testing you have. If I were you I'd let my robot do a couple of hours moving around including the water line. At least it would work for the pool as the spa would need manual brushing.

 

[KJB1]

KJ
You haven't filled in your signature with what equipment and testing you have. If I were you I'd let my robot do a couple of hours moving around including the water line. At least it would work for the pool as the spa would need manual brushing.

I use k-2006 test kit. Equipment I will update my signature today with exact specs. All new Hayward VS pump, cartridge filter.
I started a SLAM last night, I’m tired of being worried all the time. I lost 2.5ppm chlorine last night. Maybe a testing error, I have never counted 50 drops before and my vision was getting cross eyed. I’m continuing today.

 

[an1vrsy]

With the K-2006 test kit, use 10 ml sample, one heaping scoop of powder, then each drop will be .5

Youll be able to save on reagents that way.

 

[KJB1]

With the K-2006 test kit, use 10 ml sample, one heaping scoop of powder, then each drop will be .5

Youll be able to save on reagents that way.

Copy that. I ordered the 16oz reagent drops today. Slamming uses a ridiculous amount. I should be set for the year with the big gulp size .

 

[KJB1]

Last night lost somewhere between 1-1.5ppm. I am not 100% accurate when testing at these levels. I try to do exactly the same timing on drops but get slightly different results on back to back tests. Within 2-4 drops variance out of 44-48 drops (shooting for 24ppm). I guess that’s within the 10% margin of error but makes it difficult when trying to measure .5-1ppm loss.
Continuing the slam today, I’m back to work and expecting rain so it may be difficult.

 

[mknauss]

I guess that’s within the 10% margin of error but makes it difficult when trying to measure .5-1ppm loss.

That is why following SLAM process at high CYA is tough.
If you have crystal clear water, with no debris build up (dead algae), then let your FC drift down to 10-15 ppm and do the OCLT.

 

[KJB1]

Water looks great and nothing at all to vacuum or even brush this morning. Yesterday just wind blown debris needed cleaning up. Very minimal. No evidence of any algae at all since starting SLAM.

Thanks for the advice. I’ll let the chlorine level drop after today and report back later in the week. If I need to SLAM again, at least it will be cheaper with the shorter and cloudy days of fall starting soon. I picked the 100 degree weekend

I’m also going to order the 50ppm sample for the CYA test. I can’t figure out if I’m at 60 or 50, it depends on the lighting. Not usually a big concern but it’s a pretty good amount of chlorine when SLAMMING.

 

[KJB1]

I did 2 tests at night and 2 in the morning. Variance between 1.5 and .5 chlorine loss @ 24ppm FC. I’m calling it a success. Got my 16oz reagent so no fear of waste or running out anymore. We had thunderstorms overnight too. I honestly expected more loss. I’ll do another OCLT when I get closer to 10 as recommended.

 

[KJB1]

Finally got down to a reasonable chlorine level. 10.5ppm last night 10.0ppm this morning and no signs of any algae for over a week. Going to keep it at 10ppm for a couple weeks following the mustard algae min. level to be safe.