Help with first SLAM

[Hootie]

Hi everyone. New pool owner and learning as I go. Subscribed to Pool Math App and read pool school. Confused and need some clarification. Our pool has green algae growing on the floor/sides that ive been brushing off and then shocking. It’s not a ton just a few spots around the side, and it also is growing on the returns and light. The water is otherwise clear. The algae kept returning so i started reading online and ended up here. Now I'm at:
FC: 18
CC: 1
CYA: 40
pH: 7.4
TA: 120

It’s a vinyl pool approx 28000gal, SWCG. Prior to starting SLAM my FC was pretty much 0. I assume the algae was consuming chlorine faster than SWCG was making it. I’ve added about 25gal of 6% bleach since Friday night and my wife thinks I’ve lost my mind. The pool looks perfect and I’m running to the store everyday with another 10 gallons of bleach like a crazy person. Last night I went to bed at 17ppm FC and this morning it was 8ppm before the sun came up.
Is this normal for a pool with no visible algae?

 

[Mike1162]

Something is still consuming the chlorine. Get more chlorine & continue on. I'd remove the pool light & clean the niche. Also consider cleaning the pool filter thoroughly.

 

[Hootie]

I've never cleaned the filter besides backwashing. I'll look for a tutorial and see what happens. I think I see how the light comes apart. I'll give it a shot today.

 

[mknauss]

Pool School - Maintenance and Cleaning of Pool Filters

 

[kimkats]

I was also thinking about cleaning behind the lights and such. You might also want to take a VERY close look at your skimmer, inside and out. Think about giving your pool it's own toothbrush to use around everything in the pool like the skimmer area and returns, etc.

Let us know how the filter cleaning goes!

Kim

 

[Hootie]

Got the light cleaned out. Holy cow what a mess in there. Looks like the cable is about 20' long and someone previously wrapped it with duct tape. That adhesive broke down and was a brown goo covering everything. Hopefully the filter gets it all out of the water. But the light and niche are nice and clean now. Removed the ladder and cleaned that up (found a small amount of algae under the steps). Going to clean the filter today after it, hopefully, gets that glue junk out of the water.

While I have the light out, it's been broken since we moved in 2 months ago. Bulb tests bad. Any recommendation on LED or am I best sticking with regular? The kids like colors maybe the color changing LEDs? It's a Hayward fixture with R40 bulb. 120V 500w.

 

[mknauss]

Check with Inyopools on light replacements. Lots to choose from.

 

[Hootie]

Finished brushing entire pool again. Got detailed with the skimmers. Found algae behind the little flapper door and in the foam baffle. That's soaking in diluted bleach now. Got into every crevice and it looks a lot better. Still losing FC but will do OCLT tonight. Tomorrow I'm back at work so the dosing of the SLAM isn't going to be as precise as over the weekend. Wife still thinks I'm crazy.

 

[Mike1162]

She'll know you're a genius by the time your done! Empty the skimmer & pump baskets when you do the next OCLT. It may take a couple more days before you pass. You had a large loss last night.

 

[Hootie]

Lost 11ppm last night. Pool still looks perfectly clear. No visible leaves or algae. Brushing produces no green mist or other sign of algae.
I'm not understanding how everything looks perfectly fine yet I'm losing more FC than pools that are green swamps? I've scrubbed every return and skimmer, removed and cleaned the ladder (did not reinstall). I've put 35 gallons of bleach in since Friday night. Does this seem right???

 

[Hootie]

Just to update. Did the deep clean of the DE filter. It was caked with powder. Previous owner told me to add 5lbs every backwash. I think that's the full amount for a ProGrid 4820. I cleaned everything up and added 5lbs so hopefully it's right now. How much should I be adding after backwash?
Was hoping the filter would be full of algae and I could wipe it out, but besides the DE it looked OK to me. No green inside. Still blown away how what appears to be a sparkling pool is consuming FC by the truckload.

 

[mknauss]

Unless your pool is a green swamp your filter would not have any live algae in it. It is bathed in the same SLAM level water as the pool.

The overnight chlorine consumption will just suddenly stop. Might be tonight, might be in a day or two. Stay at it, or you will be re-doing this later.

Great job.

 

[Hootie]

Thanks for the info. I’ll keep chugging along. When this is all complete, is it normal to find patches of algae around a skimmer or return? I’m still a pool noob so I’m not sure if I encounter any algae after I’m done SLAMing if I’m supposed to just brush it and move on with life or go right back to SLAM?

 

[mknauss]

It is not normal to ever see any visible algae. Adequate chlorination and brushing of the pool surfaces will prevent algae.

If algae is present, a SLAM is indicated.

 

[Glofton]

Don’t feel bad Hootie, I’m on the 11 day of my SLAM! My pool has been crystal clear since the 3rd day of the SLAM. Ive probably been through close to 100 jugs of bleach(not exaggerating) and have scrubbed every sqaure inch of that pool everyday. However, I keep losing about 6-7ppm of FC each night.

After about 8 or 9 days I became suspicious of how long it was taking so I re-checked my CYA to make sure I was SLAMing at the correct FC level. Sure enough, I wasnt. The first time I checked my CYA, I performed the test inside and apparently did not get an accurate reading since you are suppose to perform the test outside with your back to the sun. I corrected my SLAM levels and last night was the first sign of hope I’ve had, only losing 2ppm. So hopefully I’m getting close to the end.

All I’m trying to say is...hang in there. I feel very confident these guys/gals know what they are talking about.

Good Luck

 

[discgolfdc]

To save a little coin and reduce fatigue, consider getting "liquid chlorinator" as opposed to "household bleach." The stuff that you get in Walmart, Target, Sam's Club, etc., is largely 6% NaClO by volume. I actually found that, so far in my search, the best source for liquid chlorinator is Leslie's Pool Supply near me. It's 10% NaClO, and where bleach is typically around $4/gal, my local Leslie's sells a 4 pack of gallon jugs for $13.98 (about $3.50/gal). You're using less volume and spending less. Just a thought. I've just gone through a SLAM and I'm keeping my eye on things very closely. My CYA was kinda high, so my target FC was around 26, but I OCLT'd with no loss and <0.5 CC, and my water looks great. In the words of Reagan, though, "trust, but verify." LOL

Good luck. This site saved my derrière.

 

[Hootie]

Just updating on progress. Last night went from 16ppm FC to 15.5 this morning. The difference is likely testing error (I'm using 10ml samples). CC is under .5 and water looks perfect. I think I'm done! Took about 50 gallons of bleach to get here. I'll keep FC high one more night to be sure then let FC drop tomorrow. I need to add stabilizer as well.
I see the recommendation is to have CYA at 80-90 for SWG pools. Is that because SWG produces FC slowly?
Thanks all for the help so far!

 

[ajw22]

I see the recommendation is to have CYA at 80-90 for SWG pools. Is that because SWG produces FC slowly?
Thanks all for the help so far!

Congratulations on getting the SLAM Process done.

CYA of 70 should be adequate for a SWG in NJ. We don’t get Texas sun and heat.

 

[kimkats]

Here is an older thread about the whys of higher CYA. Why high CYA is a good thing with a SWG

Kim

 

[Catanzaro]

Just updating on progress. Last night went from 16ppm FC to 15.5 this morning. The difference is likely testing error (I'm using 10ml samples). CC is under .5 and water looks perfect. I think I'm done! Took about 50 gallons of bleach to get here. I'll keep FC high one more night to be sure then let FC drop tomorrow. I need to add stabilizer as well.
I see the recommendation is to have CYA at 80-90 for SWG pools. Is that because SWG produces FC slowly?
Thanks all for the help so far!

Hootie:

I have tinkered around with CYA of 50-70 with an SWG. At present, I am at 70. The only issue is that I could not get a good feel of chlorine consumption at 50 vs. 70, because of constantly adjusting the SWG and heavy bather load. Had to add liquid at the same time. I keep mine at 70, even in NJ, but if the CYA does drop and you feel that you are consuming more chlorine than normal, then bump it back up to 70.

When I was dosing the pool with 12.5% (Thanks Ocean State Odd Job), it was very easy for me to gauge. I found that a CYA on the lower side (30-40) was perfectly fine. Even at 50, the % loss was negligible. Amazing that after working with your own pool, how quickly one can spot a problem. A big thanks to the TFP community for everything I have learned.