HELP Please!! Aquatech AT100 filter changing the sand


New member
Jun 7, 2010
Summerville, SC
2nd year in my house and this year I'm working hard to do the pool right. Spent all of last year guessing at what to stick in it and spent a fortune on chemicals with awful results. I test weekly now and I have all the levels where they are supposed to be according to the pool company. Still cloudy water. In the shallow end I can just see the bottom and in the deep its a pretty blue but i can't see more than a few feet through it. 20X40 pool 36,000 gallons. Monster. I think working with the pool people ive narrowed it down to needing to change the sand in the filter. Spoke with previous owner and it's never been changed and the pool is 8 years old and hadn't been cleaned, treated or even opened for almost 2 years before i moved in. Had the liner replaced when i moved in last year, fresh water but nothing was done to the filter. Had the nastiest smelling stuff just sitting in there for who knows how long. Anyway, the multiport is side mounted. It's a one piece tank. The pressure gauge is on top and every site ive gone to says just unbolt the cap and it gives access to everything. There aren't any bolts on the cap. Ive looked 10 times now and nope... no bolts. The manual I have for the filter has directions for a top mount multiport, no side mount. So now I'm stuck. I'm thinking (dangerous) that the cap might just be threaded into the top of the filter and if i just turn it, it will unscrew. On a side note, i was just in my garage getting pool stuff together and found a jar full of what look like laterals from a pool filter. The filter couldnt possibly be working at all without laterals in it... could it? Any help at all would be so greatly appreciated.

Bama Rambler

Mod Squad
TFP Expert
LifeTime Supporter
Jun 22, 2009
SouthWest Alabama
I'm not sure changing the sand is going to fix your problem. It's obviously done pretty good if you don't see dirty water returning to the pool. Can you post a pic of the filter and equipment pad?

Lots of things beside the filter can cause the water to be cloudy. Post a full set of test results if you can and where you go them.


That'll let us help you figure what the problem is.


New member
Jun 7, 2010
Summerville, SC
Am I the only one that finds these things totally confusing? OK, just had the water tested yesterday so I'll post the results later. The water returning to the pool doesn't look dirty. When I backwash the water is absolutely dirty, so the filter must be doing something. Argh.
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