Long term mini SLAM

Katodude

Silver Supporter
Aug 22, 2017
871
West Palm Beach/Florida
So as I read the forums something strikes me as an interesting fact. When people are SLAMing and their FC level drops below SLAM I believe I have heard that any amount of chlorine over the recommended level is still killing algae.

So in theory as long as your FC was above ideal, are you performing a mini SLAM. Obviously one that would take significantly longer than a traditional SLAM. But after some time, weeks or months all the algae would be dead? Or is this just crazy talk.

Let me be clear I am not recommending this approach just interested in the hypothetical discussion.
 

jblizzle

Mod Squad
TFP Expert
LifeTime Supporter
May 19, 2010
43,238
Tucson, AZ
FC at any level is constantly killing algae.
If you keep the FC above the minimum for your CYA at all times, you will never get an algae outbreak, but still killing anything in the water ... I would not want to use the term "mini SLAM" though

The SLAM process chlorine levels were designed to kill the algae faster than it can reproduce and to do so in a "reasonable" amount of time. As long as your FC is high enough that the kill rates are higher than the reproduction rates, you would eventually clear up the pool
 

Katodude

Silver Supporter
Aug 22, 2017
871
West Palm Beach/Florida
FC at any level is constantly killing algae.
If you keep the FC above the minimum for your CYA at all times, you will never get an algae outbreak, but still killing anything in the water ... I would not want to use the term "mini SLAM" though

The SLAM process chlorine levels were designed to kill the algae faster than it can reproduce and to do so in a "reasonable" amount of time. As long as your FC is high enough that the kill rates are higher than the reproduction rates, you would eventually clear up the pool
Fair enough, “mini SLAM” is probably a bad term.
 

Donldson

TFP Expert
LifeTime Supporter
Jun 12, 2009
4,421
NW Ohio
In theory, any level above minimum has a chance to kill algae faster than it can reproduce. That is dependent on the amount of algae though. It would also require far more testing and dosing since a decent sized algae bloom would make quick work of an FC level lower than SLAM level. Heck, it tends to make quick work of SLAM FC.

Most importantly though is the amount of wasted chlorine. You may be killing algae faster than it reproduces, but it is still reproducing and thus in the long-term you are killing more algae for the same result. Think of it like doing a water change for CYA. If you have a CYA of 100 in 10,000 gallons and want to bring it to 50, you can go about it several ways. You can drop half your water and do it in one shot, or you can do it 10% multiple times. In the first instance, you use 5,000 gallons of water, but in the second instance you would have to do your 1,000 gallon exchange 7 times and would use 7,000 gallons of water. This isn't a perfect example because SLAM should never be treated as a single shot and done, but the idea of using less than 40% FC to CYA results in similar inefficiencies.
 

Katodude

Silver Supporter
Aug 22, 2017
871
West Palm Beach/Florida
That’s an interesting point about the decreased efficiency. I did not take into effect that the algae is reproducing. Not only would it take significantly longer it would require more chlorine, which would make it take even longer still.
 

Richard320

TFP Expert
LifeTime Supporter
Jan 6, 2010
23,600
San Dimas, CA (LA County)
That’s an interesting point about the decreased efficiency. I did not take into effect that the algae is reproducing. Not only would it take significantly longer it would require more chlorine, which would make it take even longer still.
Precisely. But on the opposite side of the scale, the higher the FC, the faster the sun steals it. It's more of a half-life thing than a fixed parts per million per hour. So boosting FC too high means losing more faster. The levels were chosen to provide a happy balance between fast killing and solar losses.
 

Katodude

Silver Supporter
Aug 22, 2017
871
West Palm Beach/Florida
Ok, so lets stretch the hypothetical in the other direction. Let’s say you started the SLAM after dark. Would boosting the FC level above SLAM amounts help kill algae faster? You could keep SLAM levels during the day and go extra hot at night. Or are there diminishing returns?
 

Richard320

TFP Expert
LifeTime Supporter
Jan 6, 2010
23,600
San Dimas, CA (LA County)
Ok, so lets stretch the hypothetical in the other direction. Let’s say you started the SLAM after dark. Would boosting the FC level above SLAM amounts help kill algae faster? You could keep SLAM levels during the day and go extra hot at night. Or are there diminishing returns?
That would probably not be wise in a vinyl pool, lest you bleach out the liner. I'm not sure about fiberglass. We try to make our instructions universal.

I suppose if you were there brushing a plaster pool to expose the algae,you could accelerate things. But the fast killing is usually done in a matter of hours anyway and then the superhigh level would just burn off when the sun hit. And if you're up all night brushing and vacuuming anyway, why not just test and dose?

If someone has cleaned the piles of organic debris out of the depths before reaching for the jug, the pool goes from green to grey in just a few hours most of the time. The agonizing part is waiting for the filter to clear it. You'd save a couple hours tops.