Something is wrong w/sand filter... pump too large?

[SandyA]

Pool was opened 4 days ago with a lovely green color due to a break in our pool cover. The algae has since died (FC has been holding at 16 w/CYA at 40ppm for a few days) but b/c I noticed very large particles suspended in the pool water in the pool water after 4 straight days of 24/7 filtering thru our 14" Doughboy Powerline sand filter filled w/zeosand, I put a debris sock on the skimmer to help it along. After only 30 minutes, the skimmer sock was literally filled (I lost prime) with what appears-to-be sand filter scum, but with absolutely no sand. The particles in the sock are a very soft coagulation of synthetic and natural fibers(seems like cotton), hairs, very very minute blue flecks, and a whole heckuvalotuv other small organic Crud w/the same grayish green color as the sand. I also found it very odd that the pressure never went higher than 3psi over the original pressure of 15psi even tho a ton of debris was accidentally put into the water from the cover break. We took the sand out of the filter to see if anything inside was in disrepair but I immediately noticed how clean the sand looked.

The zeosand was changed the beginning of last season after switching to chlorine from baquacil. The water was clear last summer for the most part (except when battling cloudy water during the extreme heat). The pump and filter are only 2 years old (as is the pool-- 7900 gal 12x24). I've suspected for some time the the 1.5HP doughboy that the pool installer (has since gone out of business...go figure) supplied with the pool is much too large but I can't find any info if that size pump w/a 14" sand filter would cause any similar problems. Our Doughboy pump does not have any laterals to break (it's got an underdrain).

Does anyone have any idea what would cause the filter scum to go into the pool? Should I be looking into a buying either a larger filter or a smaller pump? Is the pump too large for our filter and what problems are encountered if the pump is indeed too large?

Thanks.

 

[JasonLion]

A large pump can cause problems for small filters. The extra water flow can cause the sand to channelize, which lets debris get through the sand. Usually you can get by despite this for some time but ideally you want a smaller pump and a larger filter.

 

[SandyA]

JasonLion, thanks for the reply. Would you recommend I purchase a larger filter or a smaller, more efficient pump? I am concerned about operating cost....electricity is not cheap in Jersey.

But....something really strange is going on. The sand was changed and within a couple hours the pool water started clearing up and the pressure finally went up 6psi (like we'd expect with a large amt. of goo) from the original 15psi after backwashing. But after running all day, I went to check on the water and the pressure went back down to 15psi all on its own. Within an hour the water started getting mucky again with that same green-gray Crud as described above. The stuff is floating at the surface of the pool in addition to being suspended.

Weird, weird, weird. Any ideas what this stuff could be.....anyone?

Took the skimmer sock w/the scum to a pool store and talked with the manager for 30min about the problem and he is totally stumped. Said he's been in the business for 25yrs. and has never seen that kind of gunk before. I'm still suspecting the pump did something to the filter.

Any thoughts on what is happening would be greatly appreciated.

 

[JasonLion]

That fits with exactly what I said. The large pump is causing the sand to channelize, which lets the debris through.

Getting a smaller pump would help all around, improve filtering and reduce electrical costs. A larger filter would be great, but it wouldn't make as large of a difference.