Richard:
I switched to cellulose for my DE filter a couple of years ago, and then my former pool guy switched back to DE because he says DE works better. After I let him go (long story), I cleaned out the filter grids and filter, and used the Pool Time cellulose from Home Depot. According to instructions, you use much less of this than DE, so I followed their instructions. I noticed that pressure runs about the same as with DE. This may be due to the reduced amount of cellulose required, according to the directions. In any event, I find this stuff backwashes just fine and cleaning is no bigger pain than with DE. This stuff cleans better than DE, by about a factor of 2 because of its smaller porosity (2 micron vs. 4-5 for DE):
http://aquamagazine.com/content/post/Po ... on-DE.aspx
After a filter cleaning, the pressure on the DE filter is around 15-17 PSI. I usually backwash or do a complete filter grid cleanup when the filter pressure gets up to 25 PSI. This depends on the weather and amount of debris, but I usually do a complete clean about every 4-6 months and a backwash about once every six weeks. When I do only a backwash, I add about 6 cups of the cellulose which returns the pressure to around 17 psi.
The difference in water quality is pretty noticeable. First, it is very clear, esp. at night when the light is on. With DE, there were always irridescent particles floating near the light. I can't really detect those with cellulose. Also, I've seen an oily sheen on the water when the kids go into the pool with oily sun-block, but that doesn't seem to occur anymore with the cellulose. So, I'm convinced it's a better way to go, and it's not going to leave DE in the part of the yard where the backflush water drains.
One comment about backwashing that may be important. When I backwash, I usually do this with several cycles of backwash vs. normal flow. I find that doing so seems to eliminate a more significant fraction of filter media than just running the backwash for a longer period of time. This is borne out by the observation of "dirty backwash" vs. clear water. If I run the backwash for a couple of minutes, the water runs clear after about a minute. If I cycle this, I find that I can get better release of residual cellulose out of the filter based on seeing new dirty backwash on each cycle. Also, when I do a complete cleanup, I notice that this type of backwash protocol leaves the grids almost completely void of filter media. This significantly reduces the number of times I need to do a complete filter breakdown each year.
I switched to cellulose for my DE filter a couple of years ago, and then my former pool guy switched back to DE because he says DE works better. After I let him go (long story), I cleaned out the filter grids and filter, and used the Pool Time cellulose from Home Depot. According to instructions, you use much less of this than DE, so I followed their instructions. I noticed that pressure runs about the same as with DE. This may be due to the reduced amount of cellulose required, according to the directions. In any event, I find this stuff backwashes just fine and cleaning is no bigger pain than with DE. This stuff cleans better than DE, by about a factor of 2 because of its smaller porosity (2 micron vs. 4-5 for DE):
http://aquamagazine.com/content/post/Po ... on-DE.aspx
After a filter cleaning, the pressure on the DE filter is around 15-17 PSI. I usually backwash or do a complete filter grid cleanup when the filter pressure gets up to 25 PSI. This depends on the weather and amount of debris, but I usually do a complete clean about every 4-6 months and a backwash about once every six weeks. When I do only a backwash, I add about 6 cups of the cellulose which returns the pressure to around 17 psi.
The difference in water quality is pretty noticeable. First, it is very clear, esp. at night when the light is on. With DE, there were always irridescent particles floating near the light. I can't really detect those with cellulose. Also, I've seen an oily sheen on the water when the kids go into the pool with oily sun-block, but that doesn't seem to occur anymore with the cellulose. So, I'm convinced it's a better way to go, and it's not going to leave DE in the part of the yard where the backflush water drains.
One comment about backwashing that may be important. When I backwash, I usually do this with several cycles of backwash vs. normal flow. I find that doing so seems to eliminate a more significant fraction of filter media than just running the backwash for a longer period of time. This is borne out by the observation of "dirty backwash" vs. clear water. If I run the backwash for a couple of minutes, the water runs clear after about a minute. If I cycle this, I find that I can get better release of residual cellulose out of the filter based on seeing new dirty backwash on each cycle. Also, when I do a complete cleanup, I notice that this type of backwash protocol leaves the grids almost completely void of filter media. This significantly reduces the number of times I need to do a complete filter breakdown each year.
