How do I know when the algae is gone?

[Janelle]

Hi there,

I just had my first bout with algae. I noticed that the water was hazy then cloudy and could feel some slimy spots in pool. I slammed pool and brushed, and the water cleared in a day. I vacuumed and brushed some more. My question is regarding my cc. Is the high cc due to dead algae that hasn't been filtered out yet or evidence that more algae is on it's way?
FC 4.2
TC 5.4
CC 1.2
PH 7.6
TA 97
CYA 26

Thanks!

 

[Donldson]

I don't normally trust pool store numbers, but if they are accurate you are not done SLAMing. The CC is from live algae being killed. You are not done until:
water is clear [check]
your CC is 0.5 or lower [nope]
and you pass the OCLT [unknown].

Bring your pool back up to shock level and keep it there until all 3 are passed. I would strongly suggest you get a kit to test your own water as well. After all, if you want something done right...

 

[chem geek]

Those numbers look like they are from a pool store so may not be accurate. You should have your own good test kit, either the TFTestkits TF-100 or the Taylor K-2006 (see Test Kits Compared.

If the numbers are accurate and you have 1.2 ppm CC, then that may be from chlorine combined with dead algae and still needs to get cleared from the pool. If the water is clear and the filter pressure rose, you can backwash or clean the filter so that chlorine doesn't continue to react with what has been caught in the filter.

Keep your pool uncovered and exposed to sunlight and maintain the shock level and the CC level should come down. When it's 0.5 ppm or lower, you are done, assuming your overnight chlorine loss is <= 1.0 ppm.

 

[Janelle]

I vacummed to waste so I didn't backwash filter because the pressure didn't go up. I guess I'll backwash filter tonight when I get home and add more chlorine. Yes, I know I need my own test kit, but funds are limited and there is a good chance that this will be my only summer with the pool, which in Michingan is only another 45 days. I already blew it by not having one from the get go when opening the pool(found this site too late).... I will definitely order a test kit next spring if still in house.

So regardless, I will bring pool to shock level today and retest. Just to clarify, is the high cc most likely dead algae waiting to be filtered or live algae?
Thanks!

 

[Donldson]

Just to clarify, is the high cc most likely dead algae waiting to be filtered or live algae?

It is the byproduct of live algae being destroyed by chlorine. Dead algae does not cause it, not does live algae that has not been oxidized. So if you have CC it means that something is reacting with the chlorine, be it algae or another contaminate.

 

[jblizzle]

How are you going to measure "shock" level? The pool store test likely only goes up to 5ppm or 10ppm at most. Ideally you need to follow the SLAM process. [slam:162o8gyo][/slam:162o8gyo]

 

[Janelle]

When shocking, I use my basic test kit to get an idea of starting fc level. From there, I use cya chart and pool calc to figure how much chlorine to add. Admittedly, I don't retest at home for cc every hour since I can't, but also throughout the day I'm at work. Since my water did clear in one day, I figure my process, although not totally by the rules, is working, albeit a little slower.

In order to avoid future algae, I know I need to maintain fc better. For the first month, pool was crytal-no problems. Then last week and continuing, we've had a stretch of sun and 90 degree days(not normal for Michigan), so the algae started. I need some advice on how to better maintain fc. I currently have a pentair automatic chlorine feeder(tablets) that is set to the max. I supplement that by adding a gallon of chlorine 2-3 times/week depending on fc test results(basic at home kit). Does this sound normal? To me, this seems like enough chlorine-but I'm clearly no expert.
thanks!

 

[jblizzle]

You just need to be using enough bleach to keep the FC above the minimum for you CYA. You also need to be careful because all the pucks are adding more CYA which will required higher FC levels.

But, that assumes you are starting with a clean pool, when you clearly are not. Since you have algae, it is consuming the FC.

To answer your title question directly: You know it is gone when the water is clear, you have no more than 0.5ppm CC, and most importantly, you pass the OCLT.