Thoughts on sand filter plus cartidge

[johndoe]

Hey guys I'll be doing some plumbing with a pool make over and have a few ideas. First off I've got a bunch of pumps and all items discussed I already have laying around.
Pool is 16x24 doughboy 48" deep, 10,000 gallons. Previous owner's setup Hayward 16"sand filter, 1.5hp pump was told it only holds 50lbs, not the 100 per instructions, nice people though! Currently single skimmer and return.
1st off I plan to swap in my 3/4 hp flowtec. I want to add a 2nd skimmer and at least 1 or more returns. Should there be any concern about number returns for a pump this size? --pool cleaner is hayward aquabug 500.
2nd I have a Intex 1500gph "wetset" 4 amp rated nameplate, I think 1/3 hp with a built in cartridge filter. I could add this in parallel, (won't run at the same time) gain extra filtration, redundancy, use a little less power, maybe less backwashing too? This pump worked great on my 15' round Intex running 8hrs a day.
3rd Any opinions on return jets, like rotating spa style? I'm thinking about one to help stir things off the bottom and or near the stair area. We get lots of leaves...

Thanks!

 

[Bama Rambler]

Your 3/4 hp pump will be fine. I'd upgrade that sand filter to a larger model and wouldn't waste time plumbing the cartridge at all. JMO.

 

[gtojohn]

Won't a cartridge filter smaller particles?

 

[Bama Rambler]

Unless you're going to install a lot larger cartridge you'll be limiting your filtering capacity. You most likely won't notice the difference in the pool.

 

[AP]

Agreed. Dump the Cartridge filter (or manual backwash filter) and go with the sand.

Cartridge will filter finer but you cant backwash. Pools need fresh water in them to get rid of UTDS and backwashing and getting new water into the pool is a great way to do this.

Keep it simple.

 

[johndoe]

Revisited, Hayward c751 and bigger sand filter

I understand simple, BUT, there's no kill like overkill! Well, 2 things have changed, 1st I was wrong about my sand filter, its the 21" Hayward 210. 2ndly I picked up a Hayward c751 cartridge filter at a yard sale today spare 1hp pump included. How about now? Poor man's 3 speed, 1 3/4 hp when needed. Plumbing, if I have a dedicated pump for each filter do I just run them parallel? Is there any need for check valves?

 

[JasonLion]

Running two filters, or two pumps, in parallel from a common suction pipe and common return pipe is problematic at best. Unless the pumps are perfectly matched the larger pump will tend to put back pressure on the smaller pump reducing it's flow rate so much that it will be essentially useless. Similar issues come up when putting two filters in parallel on a single pump. If you have independent suction and return plumbing for each pump/filter then all is good.

If you are dead set on making things over complicated, then put the two filters in series, sand first and cartridge second.

 

[johndoe]

why not run them at separate times. 5 hrs sand pump then 5 hrs cartridge. There will be 2 skimmers and at least 2 returns, hadn't considered not connecting them, but its easy to not connect them. My thoughts are for the little effort of installing these pieces I already have, I'll cut filter maintenance in half including backwashing, gain a little extra filtration over just sand and have redundancy in case of failure.

 

[JasonLion]

Running one half time and the other half time won't improve anything. Each filter will need half as much maintenance, but there are two of them, so it works out to just as much work. Also, the quality of the filtering won't be as good as if you just used the cartridge filter. Basically you will have twice as many things that can break, leading to more trouble in the long run.