First Slam tonight. FC consumption!!

May 2, 2015
28
Sherwood, AR
27,000 gal. 75F.
ph 7.4
ta 40ppm
ch 190
cyn 50
fc/tc/cc 0.

Calc 1210 oz (10 jugs) 8.25% bleach would get me to fc 30. Where I planned to get more in morning to maintain.

Tested 2 hrs after application. fc .5 (if that). tc 20 (didnt scale test to read 30).

Pool is a swamp, looking better around steps. Im now assuming this fc consumption 20/30 in 2 hours during night is possible with high contaminate.

Contemplating how to proceed. Was going to identify/quantify shock on hand. Wondering what product I should try to continue the process with in the morning.

Any Thoughts?
 
Welcome to the forum. :wave:

Use liquid chlorine to SLAM your pool. You need a lot of it and the powder contain stuff you do not want in your pool. Bleach or liquid chlorine only and get it in right away. The idea in the SLAM is to constantly replenish your chlorine and yours has dropped back to nothing.

Use the FC/CYA chart to calculate your SLAM value.....how did you get 30PPM?
 
Welcome to the forum,

Your FC level during SLAM depends on your Cya level. That's all there is to it. The goal is to stay at or just over SLAM value at all times until you are done with the procedure.
 
Ill heed the advise, but I have 5lb of 65% hypochlorite i considered throwing in the mix to get fc up. To my knowledge thus far, it would raise CH, which i held steady at 190. Another go x2, I will have spent c-note and have 30 empty jugs of bleach.
 
I hate you had to spend the money to clear it, but the only thing you can do it with properly is Free Chlorine. If you went to a pool store for everything, it would like cost you much more.

You might be able to use the Cal-Hypo, but I don't know what kind of pool you have. If you would please, add that to your Signature, before posting more questions. List your pool details there please. That way, we know whether or not you need to be concerned with high CH levels. and we know the specs of your pool to answer further questions.
 
Thank you. Added signature, but stated everything in 1st post. Stated cyn 50, but meant cya 50.
I digressed. I added 1210 oz of 8.25 bleach, expecting fc approx. 30. Tested in 2 hours (at night), it was zero. I was curious if initial dose could normally burn off so fast? Maybe CYA suspect? understand test can skew in cloudy water, but I expected about 50.

I figure something will give. 1210 oz of bleach every hour or two is unrealistic.

27k gallons, 18x36, Chlorine, Vinyl
 
What does the water look like? That is a lot of consumption, but I don't know what's in there. Sounds like a pretty bad swamp with that much FC consumption, or possibly ammonia. Either way, you're burning through FC, and until whatever is doing that is gone, it will continue. Is there a lot of debris in the pool? If you don't know, or suspect there might be, it should be a high priority to remove it.
 

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It was nearly black with 8" visibilty. Now there is some light, I see visibilty is almost 3', and its lighter green now. No debris (no leaves, etc.). My suspicion of fc drop due to contaminate, is feeling confirmed. First time, didnt know what to expect. Ill attempt to raise and hold again.

Thank you.

27k gallons, 18x36, Chlorine, Vinyl
 
It was nearly black with 8" visibilty. Now there is some light, I see visibilty is almost 3', and its lighter green now. No debris (no leaves, etc.). My suspicion of fc drop due to contaminate, is feeling confirmed. First time, didnt know what to expect. Ill attempt to raise and hold again.

Thank you.

27k gallons, 18x36, Chlorine, Vinyl

Hey, no problem and that's ok. But that explains it. Heavy load with the black water, maybe more. This is going to take a lot of FC. I can't stress enough to clear out anything left on the bottom, old leaves or other junk. This really taxes your FC by placing a heavy load on it. AZgirl is right, just keep going to shock level and do your utmost to stay there. This is true for every SLAM no matter the condition. Barely cloudy, or Black like this one, Free Chlorine is the answer. Is there any idea how much junk may be on the bottom?
 
If you have algae settling to the bottom, you should vacuum that out (worms, too). Use your manual vac and keep an eye on your filter pressure. Backwash when psi shows a 25% increase.....you may have to do it often.
 
Understood. I was planning to brush it down before bringing fc back up, but ill vacuum. Cant see the bottom. Although I cleaned the baskets prior, they fill with june bugs in the night. They are insane right now.

27k gallons, 18x36, Chlorine, Vinyl
 

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