Just opened and I see green starting to grow on my walls - Please help

[jhuehne]

I just got to the point where I thought my pool was ready a few days ago. I balanced the water to what I thought was good:

PH - 7.4
TA - 110
Salt - 3600
CYA - 90
FC - 0

I turned on my chlorinator and it's been slow to add chlorine, slower than in the past. I got 1 CC after 24 hours at 25% runtime on chlorinator so I bumped that to 75% yesterday and it's been less than 24 hours and I'm at a 5 now but I see green slimy stuff starting to grow on the pool liner near the walls at the bottom and up a bit near skimmer.

I believe I was too high on the CYA this year measuring over 100, so I drained the water down twice below skimmer and re-added fresh water which brought me to a 90 reading with my test kit before turning on the chlorinator.

I've never saw this green type of algae before in my pool and need some advice. Here are my current water readings:

FC - 5
CC - .5
PH - 7.7
TA - 120
CYA - 90
Salt - 3800
CH - 250

I've turned up my chlorinator to slam (120%) and I've ordered some polyquat 60 algecide which will take a few days to get here. Based on the water readings normally I'd try to put in some acid to lower the PH and TA. Should I do that now while trying to get more chlorine in the pool? I had some rain but not alot which could have impacted the PH/TA (happens usually during heavy rain).

I am worried about the initial CYA being too high and being a chlorine lock condition. I've never had this before and I'm unsure where to go.

Please help!

 

[thetekgeek]

You need to SLAM, but that might be difficult given a CYA of 90. According to the FC/CYA chart : Chlorine / CYA Chart - Trouble Free Pool you will need to use liquid chlorine/bleach to get to a target of FC 35 and keep it there until you pass the SLAM criteria outlined here: SLAM - Shock Level and Maintain - Trouble Free Pool

You could also drain some more water to get your CYA lowered some more to help with the SLAM. You shouldn't bother with the algaecide, it does nothing to kill algae once you have it.

The plan of attack is the same whether you drain more water or not, this is what I would do.
1: Lower PH to 7.2
2: Turn off chlorinator, set pump to run 24 hours/day.
3: Raise FC to SLAM level (for your CYA) using Liquid Chlorine/Bleach.
4: Maintain FC at SLAM level by testing/dosing at least 2 times daily (more if time is available).
5: Brush the entire pool twice daily.
6: Continue this until the water is crystal clear and CC's < .5.
7: Perform an OCLT to confirm that you are finished.
8: Enjoy your pool.

 

[jhuehne]

I didn't mention it, but my water is crystal clear now, just have the green growing. In the past I had algae that floated at the top of the water in little clovers. This is something different on my walls.

A few questions:

1) Add acid to lower the PH
2) Get more liquid chlorine/bleach to get the slam level? Can I not use my chlorinator to help with adding chlorine if I'm at a 7.2 PH? That's within their guidelines for water chemistry.
3) What is an OCLT?
4) Should I try and lower water first, re-add some fresh then do the acid?

Thanks.

 

[IceShadow]

1) Yes
2) SWCGs aren't really equipped to push your FC up to where you need it to be. If you drain half and refill you're at 50 CYA, and even that takes 20ppm of FC. You'll be adding bleach to get there, so you might as well save some runtime on the SWCG and turn it off until the SLAM is done.
3) Overnight Chlorine Loss Test
4) That would mean less chlorine needed, since you'd have lower CYA and SLAM level needed instead of having a CYA of 90 needing a SLAM level FC of 35. Your call on which might be cheaper/easier.