Calling all experts !

[LAWDAWG]

Here is the situation.
My chemicals are perfect, pool is crystal clean. The psi on the filter would read 17, but rise quickly to 25, within a day. I back washed the filter and it would drop back to 17. I was not aware that you had to add de each time you back washed. The previous home owner told me he added 4 coffee cans of DE filter aid, and that was sufficient. Troubled by the rise in pressure, I took apart the grids on the filter, and cleaned them. I discovered the grids were 30" high and 20" wide. I did some research and found the filter by those measurements should be a 60ft2 filter. Based on that I added 7 1/2 pounds of DE, not the 4 scoops the previous owner had done. When I say I added 7 1/2 pounds..the box stated 3 cups equals a half pound. So I added just over 42 cups (6 cups equal 1 pound). This was way more than the previous home owner did...with this calculation, he added about 2 pounds.

So here is my issue, and sorry for the long story. Every thing appears fine, but the PSI reads 23. The next day 24, and today 25. Did I add to much DE? Is the filter measurements correct on my part (60ft2). Why is the pressure rising?

Pool : 20,000 gallons
Pump: Hayward super II pump 1 1/2 hp
Filter: Hayward DE (60ft2 ???)
2 returns (jets) 1 collection skimmer( water just slightly above middle of skimmer)
Gunite pool with vinyl liner, 8ft deep end, 3ft shallow.


Thanks guys,

 

[duraleigh]

I cannot comment expertly on the DE capacity of the filter.

However, since your filter is obviously capturing something from your pool water, I would say your chemistry is not correct. Pollen is also a possibility....can you see any in your pool? If not, I suggest a complete set of test results.

How are you chlorinating?

 

[LAWDAWG]

Pollen is a concern, I cant see it in the water per say, however...spraying the deck off, water is yellow in color. Chlorine Tabs are used, they are on hold, ppm 3.5 but CYA is up. The rest is spot on.

 

[duraleigh]

Well, it sorta sounds like pollen may be the issue. That would very likely account for a one psi rise daily.

When you say "up", I don't know how high your CYA is but it is possible you do not have adequate FC for the level of your CYA.

I would still suggest pollen as the likely culprit but you could have inadequate FC as well.

 

[PaulR]

The convention is that a 1-lb coffee can holds 1/2 lb DE. Now, as far as I can tell there is no such thing as an actual 1-lb coffee can anymore, but still, whatever size the can is, it holds half that weight in DE. I haven't tried relating cups to coffee cans but 3 cups sounds a smidge low, if anything.

Lowballing the DE might be okay. My Hayward ProGrid manual's specs work out to 1 lb per 8 sq ft, while my bag of DE says 1 lb per 10 sq ft.
--paulr

 

[zea3]

You can get a DE scoop from most pool stores. I scoop is supposed to equal the volume of a 1 lb coffee can. I think if you measure the DE strictly by weight you will end up with the wrong amount of DE. If you could post a picture and/or any info from the label on the filter we may be able to give you better information.