New Filter & Pump - 20x40 In-Ground 37,000 Gallons

[mschulze]

Hello Everyone,

I am fairly new to pool ownership. My wife and I bought a house last year that came with a 20x40 in-ground pool (approx. 37,000 gallons). It came with a Sta-Rite Cartridge Filter and a 3/4 HP Hayward pump.
We experienced some difficulties getting our pool from green at open to clear. It took approximately 3-4 weeks. Also, during the pool season, we did not like the maintenance of our Cartridge filter (unscrew filter 8 screws, lift cartridges out, power-wash cartridges, lifting cartridges back inside the filter, screw filter tight, bleed the air out...)

We decided to invest into a sand filter system this year and I would like to ask you guys about the size filter and pump we require.

I have been to two different pool stores to get quotes and they gave me totally different prizes as well as filter & pump sizes. That's why I decided to ask in this forum for an unbiased opinion.

Information that might be useful:
- Current PVC piping is 1 1/2 inch
- 1 skimmer, 1 vacuum line
- 1 return jet
- 3/4 HP Hayward single speed pump
- STA-RITE S7M120 Filter
- Location: Massachusetts

Thanks in advance,
Mike

 

[mas985]

Welcome to the forum!

Often times, members blame algae problems on the equipment but really it is about poor chemistry management.

Trouble Free Pool

Cartridges can be pain if you do have algae. However, if you keep the chemistry right, then they can actually be a good filter to have. I clean mine once per year (12 months of operation) and it doesn't even need it.

 

[mschulze]

Thanks for your input @mas985.

Let’s say I wanted to switch to a sand filter anyway. What size pump and filter would I need?

 

[mas985]

For a single speed or two speed pump (recommended), I would get the smallest pump possible. 3/4 HP is fine for most pump lines. For a VS pump, size really doesn't matter since it is a variable pump.

For a filter, get the largest you can to minimize the amount of cleaning you must do. Especially for a sand filter as they will require more frequent cleaning than a properly sized cartridge or DE filter would.

For a cartridge, the filter size you have now should be more than big enough. But again, if you are cleaning the cartridge more than once per season, you have a chemistry issue, not a filter issue. Opening the pool can be a bit of pain with a cartridge, but if you have a filter bypass, it can make things a lot easier.

How many gallons is the pool?

 

[jimmythegreek]

You have a huge pool for just 1 return. But the issue is water balance. Shouldn't take more than 10 days to slam clean. I love my cartridge I clean it once even if pool is filthy from winter its 1 nut and done. You want the biggest you can get its never too big. Same hp pump is fine you may want a 2 speed with that aize pool maybe 1 hp so you can move water around a little better. I would change the cleaner port to a return line if possible get a robot.

 

[mschulze]

Hi, thank you for all your input. I guess I will try to keep my cartridge filter for at least one more season. I'm going to have to "bite the bullet" and buy new cartridges for $300. (still cheaper than a new filtration system)

Above is a picture of my pool. I tried marking where my suction line, return line, and skimmer are.

I understand you proposing that I make my suction line a return line and only have the skimmer for suction?

Thanks,
Mike

 

[mas985]

Are the cartridges damaged?

 

[elwood58]

That suction line, if sized properly, might be a good place to add a suction side robot. Something simple like Hayward XL.

 

[mschulze]

Are the cartridges damaged?

Yes, the cartridges are old and damaged. They came with the house. They were already used for at least 1 season before we moved in. They are completely grey and appear porous.

 

[mschulze]

That suction line, if sized properly, might be a good place to add a suction side robot. Something simple like Hayward XL.

I have a Kreepy Krauly like the one in the picture:


I have to clean the cartridges every week when I use this vacuum. Sometimes it gets clogged or it really slows down. It works, but I am not a huge fan of it.

 

[mas985]

The color doesn't matter and they should last many years. My last set lasted almost 10 years. As for the porous look, that may be calcium. You might try cleaning them by soaking them in TSP and after that an acid bath. The cartridges are only damaged, if they have a hole in them (i.e. the media is torn). Can you post a picture of the cartridges?

As for a cleaner, you are better off with a robot that does not require a pool pump to operate. Like one of these:

Doheny's Discovery, S200, Active20, Triton owners club

But even with a standard suction side cleaner, you shouldn't be needing to clean the cartridges every week. It sounds more like you had an algae issue with the pool which will clog a filter very quickly.

 

[jimmythegreek]

I wouldnt spend 300 on filters if you plan on replacing, a few hundred more gets you a new filter. you definitely have/had algae if your vac clogged the filters in a week. its not ideal to have such a large pool with 1 skimmer and 1 return, that is very poor circulation for that size. first thing you need to do is get a test kit. if your water is kept balanced you will be FINE with what you have. can you take a pic of your equipment pad for me too plz. you also said you have a suction port and the vac goes to it. is there a cover on the port? take a pic of it also. if its open it is NOT safe at all to have little ones or anybody in the pool with the pump running. hopefull you have a valve to isolate that port. I dont know what you wanna spend getting this pool setup, but if the only reason to change the filter is the cartridges then just do as @mas985 suggests and clean them well. get a test kit ASAP the tft test kits are great get a speed stir. We/I'll help you get your water balanced right your algae will be gone with sparkling water and the filter will work fine. as long as you dont have holes it the elements the color doesnt matter. you can soak them in a storage tote and clean them up well. Id bet my pool you have lousy water chemistry and you are going by the pool supply stores recommendations. they are clueless they wanna sell you stuff even their testing is lousy

 

[Vector]

Welcome to the forum!

Often times, members blame algae problems on the equipment but really it is about poor chemistry management.

Trouble Free Pool

Cartridges can be pain if you do have algae. However, if you keep the chemistry right, then they can actually be a good filter to have. I clean mine once per year (12 months of operation) and it doesn't even need it.

I have a cartridge too...sadly, i didn't clean it for 3 years and pool water was actually perfect. I filter all the input water through carbon though, and have very ontop of the chemistry..when i cleaned it they were dirty..i washed them good w/ a hose and soaked 24 hours in TSP, then re washed w/ a hose...pretty good.