To SLAM or not to SLAM

[sivart]

I am a relative newbie to the TFP methods having started about a month ago. I've read the SLAM page and some other info I could find regarding SLAMing the pool, but I still have a question about it. Here are my test numbers:

PH 7.5
FC 9
CC 0
TA 85
CH 275
CYA 70

I drained half the pool a month ago to get my CYA number down from 140 to 70. I have been using only liquid chlorine since that time. I was maintaining an FC level of 8 until I noticed a little algae on the sides of the pool 3 days ago. I then raised it to 9, brushed the pool and did an OCLT test that night. The FC loss was zero. It is now three days later, and I see a very slight amount of algae in a couple of spots. In the past month, I have done 4 OCLT tests, and have never lost more than .5ppm, and my CC's have been at 0 for the past few weeks. The water itself is very clear. So should I SLAM the pool? If so, how long do I SLAM for? If I follow the SLAM instructions and brush once per day, I'll have passed all of the "You are done when" items on day one.

 

[jblizzle]

Well, there is a reason there are 3 conditions to stop the SLAM, one being the water is crystal clear (which includes no visible algae).

It is possible, obviously, to have a small level of algae without the CC or failing the OCLT.

I would suggest following the SLAM process, aggressively brushing the trouble areas. Likely you may only need to do this for a day or maybe 2 since you expect the CC and OCLT to not be a problem.

 

[sivart]

That is what I was considering doing. I get that there are the 3 conditions to stop the SLAM. It's just that the SLAM process requires daily brushing during the SLAM. If I brush daily, I'll never see algae with or without the SLAM. With the other two conditions passing, I wanted to get an idea of what the reasonable amount of time to keep the SLAM going would be. I'll try a day or two as suggested. Thanks for the reply.

 

[matimer]

What kind of algae do you think you have? Any details?

 

[borjis]

Well the thing is, you need a LOT more chlorine than 9ppm with a CYA of 70 to eradicate the algae to prevent its returning.
And you definitely have to brush daily to bust off the protective bio film of the algae to wipe it out completely.

The slam will probably go quickly if you follow the procedure, I'd guess 3-4 days at the most.
As long as you maintain the proper shock level at all times.

 

[sivart]

It's green algae. It's a little hard to tell because the diamond brite surface is blue so the pool has the lagoon look, but it isn't mustard algae. It's supposed to rain here over the next couple of days so I think I'll start the SLAM after that.

 

[jblizzle]

Why wait? The lack of sunlight will mean the FC is not burned off as much if it is raining. You can be sure the algae will keep multiplying while it rains.

Amuses me when people balk about doing the chemistry on a pool because they might get wet

 

[sivart]

I just figured it would be harder to maintain the shock level if there was a lot of rain diluting the pool. I guess it would have to be a really big rain to change it too much, and it would be nice to have the clouds help keep the FC level up.

 

[Casey]

By waiting, the problem only magnifies itself.

One must treat the water with chemicals no matter rain or shine.

 

[BattleOfYakima]

Agreed, if the sun is feeding algae, they are multiplying. Bacteria are multiplying too. The more contaminants you have total, the more bleach you'll have to use eventually - whether that is during a SLAM or battling it for weeks/months playing catch-up.

A SLAM with water that is pretty good isn't too demanding in the vast majority of cases. I once had a SLAM that lasted 1.5 hours and only three bleach additions. I've had a few 2 day slams, and two swamps that were over a week! Bottom line is - as soon as you have time, handle this right before it gets worse is my vote.

 

[sivart]

I started the SLAM yesterday. It has been an annoying process, because the 12.5% liquid chlorine I purchased from Leslies is certainly not 12.5% - I think it is closer to 7%. I looked at the date code, and it was manufactured last August. I had to bring my pool up to FC of 28ppm. The calculator said that would take a little over 4 gallons of the 12.5% liquid. That amount only brought me up to 20ppm. So I ended up needing to add quite a bit more. I called Leslies, and they confirmed that it has been in the back since last summer, and they gave me a store credit for all 3 cases. Apparently, they rarely sell the stuff. I went to Lowes and purchased some 10% that was manufactured this year.

It will be nice when these CYA levels fall some more. Having to add 56 drops for the FAS-DPD test is going to burn through my test kit quick.

 

[jblizzle]

You can use 5ml of water for the FAS-DPD test so each drop is 1ppm as a rough guide. Need to go back to 10ml when trying the OCLT though.

 

[BattleOfYakima]

I looked at the date code, and it was manufactured last August. (...)I went to Lowes and purchased some 10% that was manufactured this year.

No harm in politely explaining the date situation to the store and asking for a refund or 50% refund or discount towards next purchase. Corporate always an option too. Frankly, it is pretty wrong to be selling shock that is over 6 months and still charge full price...but probably not illegal...

Congrats on the Lowes score. Many TFP followers living outside CA, AZ, or FL simply abandon the 10-12% stuff and live on the generic 8.25% bleach with a fresh date at most megamarts. At least you get what you pay for.

 

[RobertScalchi]

Your numbers look good. 20 ppm FC is good SHOCK SLAM numbers to maintain. You might need to just brush and filter out the small amounts of algae. But you want it to turn white and be killed during the SHOCK SLAM process.