Couple Questions on SLAM process for algae treatment

skillset

LifeTime Supporter
May 3, 2007
111
Central NJ
HI all – long time subscriber here and haven’t posted in awhile but still love reading the forum.

Couldn’t get bleach this year so ended up buying 20 gallons of liquid pool shock at Leslies, which is supposed to be 12.5%. I test daily for Cl and add what is necessary to get to target level for my pool’s CYA. I calibrated the pitcher I use to add bleach (using pool calc) for the 12.5%. Well, I think the Leslies stuff has only been giving me half the strength. I should have figured this out sooner. So, for the first time in years, I think I’ve been under chlorinating. And, I have algae now. Maybe 2 or 3 times over the years, I’ve had issues that I think may be mustard algae where the pool floor collects what looks like dirt and easily brushes away. I have that currently, but I also have patches of slimy film on parts of the walls (not the floor). I’m a bit colorblind so can’t tell if they are green/yellow/brown. The water clarity has been fine – it is not cloudy.

Started a SLAM yesterday around 630P. Before the slam, I brushed the walls to get rid of the spots with the film. Alkalinity was 80, CYA slightly over 50, and Ph slightly over 7.2. Got Cl up to mustard algae levels of 32. I did this in 2 waves, one hour apart. After adding the shock for the first wave, the water remained clear, but after adding the 2nd wave, the water become very dull looking, I wouldn’t say cloudy, but definitely not as clear.

This morning at 645A (very cloudy weather), Cl was 21. I was very surprised at how much Cl was lost overnight. I am doing each Cl test twice so I know the readings should be good. Water was clear. I didn’t go in, but felt around the areas that had the slime and they seemed ok. But, I did notice one 6” slime patch on the wall which I brushed away. I added Cl to bring me back to 32 and brushed, so I’m continuing the SLAM process. I don’t know if I have mustard algae, or not, so I’m treating like I do by using the higher Cl levels. Running pump 24/7 and using skimmer/main drain for circulation. But, here are my questions (any other feedback most welcome on the other details, too)

  • I had a pool pump repair done recently done by a pool company and the algae issue started soon after. I noticed they used their own bucket to take pool water to prime the pump. I am wondering if that could be a source of the algae? Maybe too Covid-19 sensitive, I guess!
  • Every time now I’m adding the Leslie’s stuff, and testing about 40 min later, I am consistently getting results I’d expect with 6% bleach, so I have to assume the shock lost its full effectiveness. Would anyone disagree? I’ve read threads on how one can test bleach, but haven’t tried them (Taylor kit / bathtub test). Also, could there possibly be anything else wrong with the shock that could cause water contamination? It smells like chlorine, if yellow, and is giving me chlorine rise. My wife’s telling me stop using it. I only have 3 gallons of it left so will be then using leftover Walmart bleach from last season.
  • I know for mustard algae, it’s recommended to thoroughly sanitize everything in and outside the pool. What’s the recommendation for a solar cover? Keep the cover on or off during the SLAM?
  • Similarly, what about a heater recommendation? Should this be run at some point during/after the SLAM (and for how long) so the high Cl can ensure the heater gets sanitized? I’ve been using the heater on and off the last few weeks, so I’m guessing it needs to be sanitized.
Thanks! And, happy Fathers Day to all the dads out there.
 

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
33,345
Laughlin, NV
I suggest you read the SLAM Process. You are dramatically over-chlorinating. IF you have mustard algae, that is a different process after the completion of the SLAM. You only hold MA levels for 24 hours. Mustard Algae - Trouble Free Pool

It is unlikely a bucket transferred algae to your pool.
The chlorine from Leslies may be old. Check if you have an Ocean State Job Lot store near you. They are reported to carry liquid chlorine.
Is your heater by passed? If not, the pool water runs through it continually.
 

skillset

LifeTime Supporter
May 3, 2007
111
Central NJ
Thanks! Yes - just re-read SLAM. I should be holding at 20 (and not 32) and will make adjustments. Thank you. I've been checking hourly and at 830A and 930A had to add a lot each time to get back to 32. Never had this much Cl loss so fast so it's a bit nerve-wracking for me. My paranoia makes me think there's something else wrong with the shock, but I'm almost done with it now. But, I guess even if over-chrlornating, I'd think I would just be speeding up the process but am I just wasting chlorine?

Appreciate the tips on where to get bleach. I do have an OSJL near me, so I'll give them a call. It's been a nightmare I'm sure for a lot us who understand we shouldn't be using a lot of the bleach that's out there with additives. HD and Lowes around here are all out of their liquid shocks.

The heater should be ok - water is constantly going through it, I guess, even when it's not operating. Thanks.

What's your take on the solar cover? I put it back on given the sun is out now and hoping to just prevent some Cl loss, but don't want to interfere with circulation.
 

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
33,345
Laughlin, NV
Solar cover can go on at night. But during the day you want the UV to eliminate the CC.

Going above SLAM level does not significantly speed up the process. The excess chlorine is lost quickly when the sun hits the pool surface.
 

skillset

LifeTime Supporter
May 3, 2007
111
Central NJ
Thanks again - will remove the solar cover.

The Ocean State Job Lot was a good suggestion for liquid chlorine. I just called the one in South Plainfield NJ and they have stock. Also, Pelican pools (NJ and PA) said they have 2.5g refillable containers.
 
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BowserB

Silver Supporter
Jul 29, 2018
363
Katy, Texas
Skillset, I think we're using the same chlorine from Leslies. It's labeled "Blue Whale Shock Chlorinator" and 12.5%. Generally, where I live it has been the best value in terms of $ per quantity of actual chlorine. At $16.99 for four gallons it's cheaper than Walmart when you take into account 12.5% vs 10% and way cheaper than our supermarket's house brand 6%. That said, I'm also wondering about this Leslies chlorine recently. It does seem that I'm using more the keep the same levels in the water. I find no date code on the plastic bottles or the box; only a Lot no. which has no meaning to me. G1350? I've tried contacting the manufacturer, Haas, Inc. but heard nothing back. Still considering SWCG, but every time I look at What's New here on tfp, I get scared away again!
 

skillset

LifeTime Supporter
May 3, 2007
111
Central NJ
BrowserB - yeah I agree but I think we're using different products. Every year for the past 10 years, I look at SWG and figure it's just as easier to just use bleach with a daily test. I've pretty much gotten great results over the years using the BBB method. What was different for me this year was my new solar cover, a pump repair, I used leftover pucks (maybe 10 1") from YEARS ago to add some CL and CYA to the water, and the Leslie's product. I agree it was a good value IF you get full strength! The bottle I have is labeled "SUPER SHOCK" and made by New Haven Chor-Alkali LLC out of New Haven, CT. There's an ink stamp that says 111019, so if this is a date, this product is old. You're making me think I should call Leslie's and and ask for a partial refund.
 

skillset

LifeTime Supporter
May 3, 2007
111
Central NJ
lol! It is giving me some lift. When I add, I test 45 minutes later to see what I actually got. I know I'm losing some Cl to sunlight in the 45 min. Most of these gallons are giving me what 6% bleach usually gives me so not a total fail - I'm measuring as though it's 6% and getting ok results. But, buyer beware. This is what makes me wary about buying stuff over 8.5%, but guess no choice today since all the bleach out there is loaded with additives. All the walmarts around here have bleach SKU's but there are cleaning, fabric protection, low splash, scented....none have the stock of the plain old bleach I've been buying for years. I wonder if they are still making it?
 

skillset

LifeTime Supporter
May 3, 2007
111
Central NJ
Marty - ever hear of losing CYA from a SLAM? I finished the SLAM (once OCLT was successful) and then added more Cl to try to keep at Mustard Algae shock level for 24 hours. Pool looking good - walls nice and clean. After the 24 hours, I've been letting Cl drift down. Tonight it was 6.5 and ran other tests results, Ph at 7.2, Alk at 80, and CYA at 35. I did the CYA with 2 different samples. Anytime I do that test, it's in full sunlight. When I started a few days ago, I tested CYA over 50 (also did this twice). I don't recall reading on the forum a case for CYA loss, so really not sure what happened. I guess I have to chalk it up to bad testing, but just wanted to ask....
 

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
33,345
Laughlin, NV
Testing error on CYA testing is +/- 10 ppm. So Your current CYA of 40 (round up) vs the 50, not all that surprising. I suspect you backwashed the sand filter at least a couple times, right?
 

skillset

LifeTime Supporter
May 3, 2007
111
Central NJ
Got it. maybe I’ll add some cya. Will full sun and the pool water at 89 degrees today, the chlorine reduced from 21 to 6.5 Between 7a and 5p, pretty drastic.

Nope - didn’t have to backwash once. Pump pressure went up 2 psi during the process and dropped the 2 afterwards which is strange to me. So, basically I’m where I started (minus the algae and a lot of chlrorine containers !)