Is is pollen, dirt, or algae?

[rshackleford]

I've been wondering the same thing.
I'm a newbie and I thought I finally got a SLAM to work right. I had a couple false starts because I didn't follow ALL the instructions. I didn't get my own complete test kit so I was relying on the pool store to get my CYA number. In two weeks I got four different readings (25, 100, 55, 40) across two different stores. I finally ordered what I needed for my CYA test. I finaly got my chlorine levels right and three days later, no change. I realized I had left the ladders in the pool and I found a ton of algae growing on the bottom of the rungs. Three more days still no change and I was loosing 3-4ppm of chlorine at night. Then I found a skimmer basket full of leaves and two albino dead frogs. I think that was where my chlorine was going.
Finally my water is crystal clear and I'm passing the OCLT test but every morning there is still a very fine layer of what I think is algae on the bottom and some on the angled sides of the deep end. Not too much on the vertical sides.
It seems like the amount goes down every day but it never completely goes away.
How can I verify if it is algae, or dust and pollen?

 

[chem geek]

Re: at how many PPM can algae NOT grow?

Finally my water is crystal clear and I'm passing the OCLT test but every morning there is still a very fine layer of what I think is algae on the bottom and some on the angled sides of the deep end. Not too much on the vertical sides.
It seems like the amount goes down every day but it never completely goes away.
How can I verify if it is algae, or dust and pollen?

If you can collect some of the material then algae feels slimy, pollen feels squishy, and dirt feels gritty. A more definitive way to test is to look under a microscope where algae is usually oblong and is translucent (i.e. you can see inside of it), pollen is usually round and often spiky and is solid and usually yellow/green though sometimes reddish, while dirt is usually oblong and is solid and usually brown.

Three more days still no change and I was loosing 3-4ppm of chlorine at night. Then I found a skimmer basket full of leaves and two albino dead frogs. I think that was where my chlorine was going.

There is no question that having any sort of debris in the skimmer or pump basket or filter that is nitrogenous and can consume chlorine will most definitely be a big source of fairly high chlorine demand. In the skimmer and pump basket in particular, the water flow rate is high so the constant exposure to fresh chlorine means it will be consumed more quickly. In the filter it depends on the filter type since the water velocity in an oversized cartridge filter is very slow.

 

[rshackleford]

Re: at how many PPM can algae NOT grow?

If you can collect some of the material then algae feels slimy, pollen feels squishy, and dirt feels gritty. A more definitive way to test is to look under a microscope where algae is usually oblong and is translucent (i.e. you can see inside of it), pollen is usually round and often spiky and is solid and usually yellow/green though sometimes reddish, while dirt is usually oblong and is solid and usually brown.

Any suggestions on a technique to collect some? seems like it might be kind of tricky. Maybe a small suction bottle held down near some on the bottom and try to suck it up?

There is no question that having any sort of debris in the skimmer or pump basket or filter that is nitrogenous and can consume chlorine will most definitely be a big source of fairly high chlorine demand. In the skimmer and pump basket in particular, the water flow rate is high so the constant exposure to fresh chlorine means it will be consumed more quickly. In the filter it depends on the filter type since the water velocity in an oversized cartridge filter is very slow.

How about a sand filter? Could not backwashing it regularly be a source of chlorine loss and possibly also a source of algae growth if the proper chlorine level isn't maintained?
My pressure gauge never raises more than 2 psi and so I don't backwash more than once a week. When Im SLAMing I backwash more often but it almost seems to me that the filter works a little better when its dirty.

 

[pabeader]

Re: at how many PPM can algae NOT grow?

a turkey baster would work, i would think.