How can I tell if it is Algae ?

[dlaslo]

I have a FC of 3 and CYA 0f 50-60 salt is about 3150 ppm and it's been hot here so we left the solar cover off. We have a buildup of a green powder around the floor circumference -- it isn't attached and easily sweeps away like talcum powder. I was able to vacuum it and the pool water is clear. I thought it was algae but my wife claims algae will attach to the walls and floor. Also thought it might be pollen (like that which covers my BBQ grill). I also put DE in my sand filter before I vacuumed since it looked real fine particles.

Not sure if I should shock or not. Is there a way to be sure?

 

[JVTrain]

I would attempt a OCLT to determine if it's pollen or algae. From the description it sounds very much like algae (goes away in a puff when you sweep) but could be settled pollen. Brush the pool well then raise the FC to 5 ppm at dusk, measure to verify your FC to get your starting FC for the OCLT. Be sure to turn off your SWG for the duration of the OCLT until you test again in the early morning.

Pool School - Perform the Overnight FC Loss Test (OCLT)

I like to do the OCLT at 5 ppm or so (minimum 3 ppm is recommended) just to be more definitive about FC loss.

 

[dlaslo]

Vacuumed and brushed the pool - & spiked the Cl- with Clorox from 3 to 5 ppm

DPD readings:

FC last night at dusk = 5.0 ppm
FC this morning at dawn = 4.5 ppm

Water is clear and green "powder" buildup on the floor is gone

Filter pressure drop has increased 5 PSI overnight - water flow is down quite a bit. I'll backflush after coffee

 

[PAGirl]

I've had both pollen and algae in the spring. The algae "poofed" into the water, the pollen tended to clump together and appear fibrous. I also found pollen on the top of the cover, on the patio furniture, etc.

 

[JVTrain]

Since your FC loss was less than 1 ppm, I'd say you're dealing with pollen and/or dust rather than algae.

 

[dlaslo]

Since your FC loss was less than 1 ppm, I'd say you're dealing with pollen and/or dust rather than algae.

I thought so too, but after the test, we vacuumed the pool again - two days in a row, and put the solar cover on. I left the FC at 5-6 ppm instead of the 3-4 I had used historically
Today....the green / yellow yuk is back - all around the perimeter

As a precaution, I dumped a gallon of clorox and a bag of Shock I had on the shelf and doubled the Hayward Cl- generator setting. I put the pump at its highest speed. After it all mixes, I'll measure the FC and adjust fro the proper slam level and I'm also thinking of vacuuming again -- I can't believe it is pollen, however the overnight only ate a half a ppm of FC indicating it isn't algae

I made an attempt to photograph it - it looks black but it is really dark green and yellow.........the fine dust gets into the cracks and crevices in the pool floor and the wall/floor interface - but nowhere else.....After putting DE in the sand filter and vacuuming last time, I backwashed until the filter pressure was low again.

 

[duraleigh]

It is algae. You need to SLAM the pool. Your SLAM will be very brief but you still need that high level of FC to kill ALL the algae in your pool.

Don't return to your 3 ppm FC. This time of year, I would not let it go below 5 ppm.

 

[JVTrain]

Yeah. Now that you posted a picture, that's algae. Tends to settle in little waves like that when it's first starting in the pool. I had a few small wisps like that in late July when my FC dropped to 3.5 ppm one weekend. With water temps near 90 now, I'm maintaining more like a 5 ppm minimum after dealing with that little bloom. (40 ppm CYA)

 

[dlaslo]

I have the FC at 25 ppm for 2 days now. (CYA=60) Yesterday it appeared nothing was happening but today the algae is almost all gone. I think I'll give it another day. The OCLT was fine before and I still got this "bloom"......Wonder what is going on? Maybe the recommended FC for salt should be a little higher?

 

[PAGirl]

I have the FC at 25 ppm for 2 days now. (CYA=60) Yesterday it appeared nothing was happening but today the algae is almost all gone. I think I'll give it another day. The OCLT was fine before and I still got this "bloom"......Wonder what is going on? Maybe the recommended FC for salt should be a little higher?

3 is the bare minimum. If you have a higher swimmer load, or something that would use up a little FC, you
Will be below the minimum. The target is 4. ( basing the 3 on your original post)

 

[dlaslo]

We vacuumed yesterday and the dead algae clouded the pool. I ran the filter 24 hours and this morning, the pool is almost crystal clear again. Maybe needs a little DE again in the sand filter to get it really clear. I started to brush the walls and my wife objected that the "dust" will only end up somewhere else in the pool if I brush without a vacuum. My thoughts were - the walls can't be easily vacuumed so they need to be brushed. If any settles, it won't settle on the walls and we vacuum later. But she won, and we didn't brush.

 

[AimeeH]

I can't say this enough

Brush brush brush. Algae develops a biofilm that actually protects it from the chlorine. Brushing it up will ensure timely algae death. Look for hiding places like behind skimmer plate and behind light faceplates. Brush. Yes it will "cloud" your water but you want all that suspended so your skimmers can get it filtered. DE won't hurt.

To win the battle, brush and then brush again anything you think you might have missed.

Ask me how I know.

 

[pooldv]

Brushing solves lots of problems in pools.