Brown dust

[domct203]

tested pool again at 10.30 this morning (since 4pm yesterday ) it is at 30ppm. CYA is 75 /80 .

Brushed twice today, and also cleaned filter again (from the overnight running) it had SOME green but very little and washed away easily.

I know I need to pass the overnight, but I have SLAMed enough times to have a really good sense of the FC drops and when it flattens out. I want to leave the SWG off while I am away so the FC can drop naturally, to a low enough level for the kids to be able to swim at the weekend. Will take another reading in an hour to see the drop today. Just a big waste of test supplies to keep testing at 28+. I presume even while the FC is dropping a bit, it will still kill the algae at FC 22+ , right ?

If your CYA is 80ppm, your SLAM FC level should be held at 32ppm, why are you targeting a FC of 28ppm?

The farther your FC falls below shock level (40% of CYA) the slower it's kill rate. I can't comment on how effective a FC of 22ppm (27.5%) would be in your situation.

You mention "I have SLAMed enough times to have a really good sense of the FC drops", I'm not sure what that means. I've had my pool 4+ years, and have only had to SLAM it twice. In theory, if FC is maintained at the proper level, and the pool is kept clean of organics and other contaminants, one should never have to SLAM.

BTW- It's perfectly fine to swim as long as the FC is above the minimum, and below the shock level for your CYA, pH is in the 7.2-7.8 range, and you can clearly see the bottom.

 

[PAGirl]

When your SLAM is over, be sure to brush regularly. It's especially important when the pool isn't being used much.

 

[simonoaks]

If your CYA is 80ppm, your SLAM FC level should be held at 32ppm, why are you targeting a FC of 28ppm?

The farther your FC falls below shock level (40% of CYA) the slower it's kill rate. I can't comment on how effective a FC of 22ppm (27.5%) would be in your situation.

You mention "I have SLAMed enough times to have a really good sense of the FC drops", I'm not sure what that means. I've had my pool 4+ years, and have only had to SLAM it twice. In theory, if FC is maintained at the proper level, and the pool is kept clean of organics and other contaminants, one should never have to SLAM.

BTW- It's perfectly fine to swim as long as the FC is above the minimum, and below the shock level for your CYA, pH is in the 7.2-7.8 range, and you can clearly see the bottom.

Sorry, I didn't mean the amount of times I have SLAMed, I meant that I hae have done two really long ones, when I first took over doing my own pool, it was a mess....the people before me had a clueless pool person who was even putting in Dicol tablets into the SWG pool. So I spent about 4 months of balancing it and getting it perfect, then had a little hit of algae again a couple of month after. That was about 3 years ago, this is now my first outbreak since then.

I mean, that I did a LOT of bleach, and measuring during that really big SLAM, and got to get a very good feel for the pattern in terms of huge drops early on then, less and less over time...... so that it is pretty easy to tell when the FC is no longer eating the algae. For example my 1 ppm drop in 18 hours....even without overnight test. I have always taken good care and kept FC around 7 , even in winter.....so not sure how this algae came about...could it be because I did not brush for a couple of months? Or maybe because my CYA dropped and SWG was not creating enough FC? I went out of town for about 1 week, so was first time in 3 years I did not do a weekly test, when I tested I was at .5ppm.... maybe that was enough for the algae?

thx

 

[tim5055]

You can look to one place if algae comes back, too little chlorine for the CYA level. CYA "dropping" would only mean that you need less chlorine.

You list "Florida" as a location, but there is a big difference between a pool in Jasper (north Florida) and one in Homestead (South Florida). Can you please update your location and signature to let us know?

 

[simonoaks]

Ok. thx.

I just measured, FC at 28, so down 3 in 1.5 days with SWG off.

As I am away again on business this week, leaving today until thur, I just added another gallon of bleach which will raise it to 32, and turned the SWG back on to maintain it while I am away. I swept and did see some tiny amounts of dust in a few places.....

I always wondered about the CYA loss. I know if say there is a storm, or I overfill pool and lose water, that it then gets diluted, but I seem to find I need to raise it about once every 8 months from 30 to 80. Is that normal, what else can cause CYA loss?

I am just by Juno Beach

 

[simonoaks]

Ok. thx.

I just measured, FC at 28, so down 3 in 1.5 days with SWG off.

As I am away again on business this week, leaving today until thur, I just added another gallon of bleach which will raise it to 32, and turned the SWG back on to maintain it while I am away. I swept and did see some tiny amounts of dust in a few places.....

I always wondered about the CYA loss. I know if say there is a storm, or I overfill pool and lose water, that it then gets diluted, but I seem to find I need to raise it about once every 8 months from 30 to 80. Is that normal, what else can cause CYA loss?

I am just by Juno Beach

 

[tim5055]

I always wondered about the CYA loss. I know if say there is a storm, or I overfill pool and lose water, that it then gets diluted, but I seem to find I need to raise it about once every 8 months from 30 to 80. Is that normal, what else can cause CYA loss?

I am just by Juno Beach

CYA naturally degrades 1-2 ppm per month. Other than that it really doesn't disappear except in some special "green pool" situations.

Do you have an autofill or have you had to add water regularly? I had a friend who had his CYA dropping like yours and it turned out to be a cracked pressure she pipe causing a slow leak. His autofill was masking the water loss.

 

[simonoaks]

I manually fill....however, here in FL, it is a lot more all year round than most, I guess. Maybe if I slightly over fill each time, it then self levels , so could be getting a small loss that way. I lose about 2 inches per week , is that about right ?

 

[tim5055]

I manually fill....however, here in FL, it is a lot more all year round than most, I guess. Maybe if I slightly over fill each time, it then self levels , so could be getting a small loss that way. I lose about 2 inches per week , is that about right ?

Unless water is physically leaving the pool (pumped out, overflowing the top, draining out of an overfill drain) CYA does not go down. When water evaporates the CYA stays behind.