I dont understand why it's green again

[Stephers]

Hello!

We opened the pool this year to a green mess with high ammonia and no cya. We cleaned up the debris and slammed it for weeks. I literally put in 30+ gallons of 10% bleach in there. The ammonia was eating it up immediately. It eventually started stabilizing and I got the cya up to 40 and eventually it got crystal clear and passed the overnight chlorine test.

We then went to get the swg going. Did an acid clean on the cell and got it going. I raised the cya up, a little too much, to 90. The swg was keeping the FC at 10 ppm.

We had wanted to do a deep clean on the sand filter, I'm not sure it's ever had one, and forgot earlier. The flow was reading pretty low. The pool still looked great at this point. Deep cleaned it 2 days ago and oh my was it dirty. Flow went up substantially. Then I noticed yesterday there was a film on the pool bottom and it was a little cloudy. I thought it might just be pollen. I vacuumed the pool and checked levels. Today the pool is fluorescent green! I dont understand why. I never let the fc go below 9. I'm going to slam again, but I'm just confused. Was it the deep cleaning?

Pool is 20,000 gallons, vinyl. Here are the levels as of last night:
Fc: 9
Cya: 80
Ph: 7.8
Ta: 80

Sorry about the novel! Thanks!

 

[mknauss]

Welcome to the forum!
Fluorescent green -- is it cloudy? Any chance of metals?
The low circulation could have compromised you. But first, how about a picture of the pool?
I suggest you read ABC's of Pool Water Chemistry and consider reviewing the entire Pool School eBook.

 

[Stephers]

Thanks. It is cloudy. I've read most of the stuff on here already. This is only our third year with the pool. It came with the house. How would I know about Metals?

 

[mknauss]

If it is cloudy it is most likely algae.
Do your sinks or toilets get stained? Read Stains in Your Pool - Trouble Free Pool

 

[Stephers]

I don't think we have a metal problem. We have city water and don't get stains.

 

[mknauss]

OK. Then SLAM. Be sure to remove the light from its niche.

 

[tim5055]

Did you use any algecide in your clean up process?

 

[Stephers]

No. Only Slammed it with liquid chlorine.

 

[tim5055]

No. Only Slammed it with liquid chlorine.

OK, last question for me (trying to find source of metals if any), do you have a pool heater?

 

[Stephers]

OK, last question for me (trying to find source of metals if any), do you have a pool heater?

We have a solar panel heating system. We haven't used it ever because haven't quite figured out how it works. But the valves in the plumbing are closed to it.

 

[Casey]

That's definitely florescent green!

 

[tim5055]

What water system do you get your water form. Most of them have an online system where they show their water quality reports. maybe there are metals tere

 

[borjis]

This is going to sound a bit crazy, but even if your municipal (not a well source) water has low
metals, it is possible to accumulate just enough over time that at some point when adding chlorine turns the water green.
(for me this is opening day) as I have no need to add chlorine from early december to late february (water temp below 45 degrees)

This happens to my pool every other year. I don't know why, but it just does. It's just enough metals
to see a green tint in the deep end. Shallow end you can barely tell.
So I do a water exchange until the green is gone. Usually 2 full days of draining with a sub pump
while filling from the hose.

 

[Stephers]

Thanks everyone. I guess it's just algae. It's already back blue 24 hrs post starting the slam. Just a little cloudy now. Hopefully it was just the dirty filter and this wont happen again when the slam is done.

 

[borjis]

Excellent. Night / Day difference!

 

[bmoreswim]

Looking great! If it wasn't for it being due to algae, the green color looked so tropical!

Good job.