conserving DPD powder during a SLAM

gwtw

Well-known member
Apr 23, 2018
91
Kentucky
We opened up our pool on Monday and it is a swamp. I've been delaying the SLAM because a local store was supposed to get in some more liquid chlorine and I was waiting for some more DPD powder to arrive in the mail. I finally obtained enough liquid chlorine but I got an email today that says that my shipment of DPD powder isn't supposed to arrive until Monday now. I have a tiny amount left but I doubt it will be enough to make it to Monday. Has anyone been in this situation before and could give me some advice on how to conserve the DPD powder? After the first day, could I just add the shock amount every few hours or something? I don't want to waste chlorine, but I can't afford to wait any longer to start this slam or I will have a harder time getting it to clear up.
 

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
29,324
Laughlin, NV
If you are unable to test, adding 5-10 ppm FC worth of liquid chlorine per day is the best thing to do. Is the pool a swamp? Then you can easily go with 10 ppm. If blue and cloudy, 5 ppm.
 

gwtw

Well-known member
Apr 23, 2018
91
Kentucky
If you are unable to test, adding 5-10 ppm FC worth of liquid chlorine per day is the best thing to do. Is the pool a swamp? Then you can easily go with 10 ppm. If blue and cloudy, 5 ppm.
I've already been doing this and the swamp is getting worse. Do you think the SLAM would go faster on Monday if I did a SLAM for one day, and then shock it twice a day afterwards? I usually see the most progress the first day and SLAMS usually go quickly for me since I have a fiberglass pool. I think I have enough DPD powder to last one day but I know that I don't have enough to make it to Monday. If you think this might help, I would do all of the shocks after day 1 with Cal-Hypo so I will have plenty of liquid chlorine left for the SLAM on Monday. I feel like those jugs of liquid chlorine are "liquid gold" because I spent so much time trying to find some.
 

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
29,324
Laughlin, NV
You can give it a try. I assume you are using one scoop of powder. All you need to do is get the water sample pink.

Most areas are having no issues getting liquid chlorine. Not sure your source but you may want to check again.
 

duraleigh

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In The Industry
Apr 1, 2007
33,741
Sebring, Florida
SLAM for one day
I think you have a fair grasp of the procedure but you cannot do a SLAM for ANY fixed time period. It is only when you meet the criteria for the SLAM to end that the SLAM is finished and that requires a successful FAS/DPD test which you cannot do

Finishing the SLAM requires three things...
A. Pool water should be crystal clear with no sign of algae anywhere
B. CC's test result should be .5 ppm or less
C. You should not lose more than 1 ppm FC overnight..

If that was my pool I would dose the pool daily as mknauss suggests and then wait for the powder to arrive. TFTestkits can overnight it if you ask them.....it's quite pricey.
 

gwtw

Well-known member
Apr 23, 2018
91
Kentucky
Ok, I have to ask: How so?
I assume its because the walls/floor are slick so the algae doesn't stick to the walls/floor as easily. I'm also very anal about brushing and backwashing often during a SLAM. I brush several times each day and backwash once a day, if needed. As soon as I can see the floor, I vacuum once a day if it needs it. I also make sure CYA is 30 when I start and use liquid CYA if I have to add some since it won't get washed out as easily. I've never had a SLAM that lasted more than 5 days but this year will probably be the exception since I'm waiting on the DPD powder.