Clear Water but algae returning

[MPR87]

Hi everyone. need some help. Fairly new to pool ownership. I’ve been all over this site and it has been very helpful so far. My pool has been crystal clear all winter and early spring while pool temp was in the 50s and 60s. Once it reach the 70s a week ago I saw some green algae forming in a few spots. I’ve been slamming for 4 days now, water has been crystal clear the entire time. I have a golf ball in the deep end, 8ft, that I can read the logo off of. I brush multiple times a day but every morning algae is back to the same spots. I pass the over night FC loss test and CC is .5 or less. I even gave my sand filter a deep clean and algae still coming back.

Last fall when I did a SLAM i very quickly started seeing the dead greyish brown algae collecting on the bottom which was telling me it’s working. I’m not seeing any of that this time.

I’m using the Taylor test kit here are my numbers.
CYA 30
PH 7.3 when I started slam
FC 15
Alkalinity 60
Vyinl in ground pool. 18k gallons. Sand filter.

Going to keep slamming. Just confused on what going on. Should I up the FC higher?

 

[ajw22]

Welcome to TFP.

Post pics of your pool and the environment around it. We have seen some pools that have water bowls or plantings around the pool that were a source of algae feeding into the pool.

 

[PoolGate]

FC of 15 and cya 30 you should have no algae. How old are your regents? Did you pass the OCLT?

 

[MPR87]

Reagent are about a year old. I did pass the OCLT. Here is a pic. I do have a large oak tree that over hangs some of the pool which drops a lot of leaves during certain times of the year but not right now.

 

[wireform]

How certain are you with the 30 CYA. If it's actually a bit more then you need to slam for 40 which may be the issue.

 

[ajw22]

Algae on your cover may be introducing it to the water every time you put the cover on.

 

[MPR87]

Haven’t had the cover on since I’ve been slamming. I’m using the K-2006C black dot test which I am not a fan of. It’s possible it’s closer to 40. I put more chlorine in this morning to bring it up to SLAM for a CYA of 40. Will see if that does the trick.

 

[wireform]

Yes, slam for 40 and brush very well twice daily.

 

[Sunny Blues]

Also, make sure to thoroughly clean every nook and cranny of your skimmer. Scrub it down well. Be sure your vacuum is also thoroughly cleaned so it’s not adding algae back into the pool either. Just a couple things to be certain of.

 

[Mdragger88]

It looks a little cloudy to me still so definitely keep going.
Go on the hunt &
Do ALL the things
*Check & scrub every nook & cranny where algae may hide {light niches, steps (inside & out), drain covers, ladder handrails, skimmer throats/weirs/weir door foam, abandoned lines, autofill, overflow drains, seam flaps, etc.}
*If water can go there, algae can thrive there.
*Run slam level water through all water features & lines for at least a couple hours a day during the SLAM Process.
*Brush & or vac daily (this breaks up biofilms that algae uses to protect itself from chlorine)
*Backwash/clean filter when pressure rises 25%over clean pressure.

 

[MPR87]

Pool looked much better today. Bumped up the FC and brushed every possible surface. Looks like I’m headed in the right direction.

Any advice on making sure I’m not reintroducing anything from the solar cover? Could I throw the cover back on for a bit while the pool is at shock level?

 

[wireform]

Pool looked much better today. Bumped up the FC and brushed every possible surface. Looks like I’m headed in the right direction.

Any advice on making sure I’m not reintroducing anything from the solar cover? Could I throw the cover back on for a bit while the pool is at shock level?

Honestly I've seen surface mold on these solar covers due to neglect so it may make sense to spread it out somewhere and brush it down with a soft bristle brush with a mild mix of bleach and water just to be certain.

 

[Mdragger88]

Also If any of your bubbles are popped its time to start shopping for a new one - once they start it only gets worse & makes it very difficult to fully clean.

 

[MPR87]

so pool was looking good. I was brushing and vacuuming multiple times a day. Had pool at slam levels for over a week. Passed the over night chlorine loss test and less then .5 cc. Was gone for 2 days. My free chlorine came down to 7.5 and it appears I have some algae returning. When I brush the bottom I get a small greenish brownish cloud getting kicked up. Water is still very clear. I am going to bring it back to slam levels again and leave it there. I just don’t understand. It’s like there is algae hiding somewhere but I have been very thorough in cleaning every accessible surface. Any other advice?

 

[wireform]

So first of all no guilt. This happens. You need to be sure your CYA is 40 and not 50 because if there's a chance it's 50 then the slam doesn't produce the results you're seeking. Also take the slam another 1 or even 2 days for insurance to be sure you got it eventhough the OCLT came clean. After make sure you stay on the hot side of the target for the CYA level you have.