Questions regarding SLAM & Brushing

[Daltex]

First of all, thank you all so much for making this site such a huge benifit for so many pool owners.

My question is why do you have to sustain the FC level at such a precise level during the SLAM?

I appreciate the fact that it does take a hyper dosage of FC to burn off the algae but if the calc. says to raise it to say FC=17 and you do this and keep it above 50% of this value until you add more bleach to regain the target FC, why wouldn't that also work? I understand that it would take longer but just trying to balance my time with results wanted.

The second thing I would like to put out there is the brushing technique I use. I have been maintaining my own pool for over 30 yrs and have had numorous green pea soup occurances out of my neglect. While back then shocking, now SLAMing, I don't brush it until I can see the bottom. This is in part do to my DE filter clogging so quickly. I get the water clear and then brush a little at a time like maybe half the walls first then let that get filtered out all the while keeping the FC at SLAM levels or close. This keeps the pool turning while I'm away from it (sleeping, work). Upon returning I backwash, adj. FC and brush another area. For the bottom if it's really bad I'll vac to waste the first time then brush. This isn't saying that brushing the whole thing at one time is bad or my way is correct but it is the only way I can have more then a few hours of circulation in the pool.

Thoughts?

 

[RobbieH]

In your example, if SLAM level is 17, you need to hit OVER 17 and keep it AT or ABOVE 17 to perform the process. Think about SLAM - Shock Level And Maintain. The first few hours, it can be hard to maintain the proper level. I recommend starting the process at night so that the sun is less a factor, but it can be done in the sun too. I go quite a bit over the SLAM level, you should be safe up to mustard algae levels - especially if you have a plaster pool. Test often, don't fall under SLAM level.

Why? Because any time you fall under SLAM level, algae has a chance to take hold again. You have to hit it and hit it hard.

 

[Daltex]

Thanks Robbie- I didn't know that algae could grow at such high levels. I always assumed that with a FC level of ie. 3-4ppm with CYA @ 40 that algae wouln't grow but just may take longer to burn off. I'm not second guessing you but I have always been able to kill off algae blooms with once a day shocks in the past. I know my FC had to take a steep nose dive while waiting for me to add the follow up doses.

Post TFP's I have been hitting it and hitting it hard. Just need a bigger hammer I'm thinking

 

[Daltex]

http://www.troublefreepool.com/threads/78262-Concerned-of-bleach-being-consumed Just read this thread and it answered my question. I may have crystal clear water but until I follow the whole SLAM procedure I could still be left with traces of algae waiting to bloom and requiring excessive bleach to maintain my FC level.

 

[bridgman]

Another point to consider is that when you do a traditional shock and it succeeds there's a good chance the initial FC level a lot *higher* than the shock level recommended here (I've seen posts talking about the entire pool bubbling) -- that gives you a decently long time above the recommended shock level but it can also be pretty hard on pool surface & equipment. IIRC the recommended shock value here is the lowest that will reliably kill an algae bloom.