Need to replace filter and have no clue what to buy after researching

poolhelpplease. said:

But if I put a 1HP impeller on it, it won’t damage the filter?

Also the C225SC works up to 84GPM while the S244T is up to 63GPM so if I understand correctly, the cartridge would filter better and last longer? I don’t understand the difference between sqft and GPM.

So if I have the chance between the 25” sandmaster with a 2” to 1.5” reducer for $180 cheaper vs the S244T2, I should go with the 25?

Sorry for all the questions. It’s just that you seem the most knowledgeable because everyone else I’ve talked to tells me that these filters work with the 2HP pump

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The Sandmaster appears to be a filter for the Canadian market so I can't say what the equivalent filter is with which I am familiar. It just may be a rename and tank color of what I know. Any filter will work with any pump right up to the point that it doesn't. The manufacturers publish design specs and parameters for a good reason, they don't want to hear complaints and accept unnecessary liability. You don't buy a 1/2 ton pick-up to regularly pull a 35,000 pound trailer. Will it work? Right up 'til it doesn't. Are you asking me to recommend something the factory doesn't? Won't do that. Will a 1hp impeller damage the filter? Read the following and make a choice. Someone mentioned that they have seen combinations of equipment that don't meet what the manufactures recommend that work. So have I, right up 'til the problems started and need correcting.

According to Hayward's pump curves (chart that explains flow rates at different head. You can look up what that means.) a 1hp Tri Star, at 40ft. of head (an average starting amount for most pools) will try to move 110gpm. That is over the design rate of a 3sq. ft. sand filter, 60gpm. Yes, most 24" sand filter are not exactly 3sq. ft. and have a rate of 63gpm. Flow rate for high-rate sand filters is 20gpm per sq. ft. You can do the math if you want to be that exact. It is also over the maximum recommended flow rate of 88gpm for 2" pipe for pool purposes. Put a 1hp impeller on that motor and you have a 1hp pump, regardless of motor power. If you were to have a .5hp impeller installed it would become a .5hp pump and the curve says that, at the same 40ft. head, the pump will move 60gpm. These are factory numbers.

A problem is that every motor school I attended cautioned against going down in size that far on a motor, which is why it wasn't mentioned. Going to .75hp is three steps down and that was the recommended limit. Going to .5 is four steps. Would it be a problem? I don't know, I'm not an engineer, and didn't really care the whys about the instructions as I am never going to design pumps or motors. I just figured that they paid other people big bucks to design these things, I took the time to attend the school, I should listen to their advice. Has served me well for over 3 decades.

I have tried to read through all the posts and here is what I agree with and what I would recommend:

1) If you like the filter you have now, stay with the same one. Installation will be a lot easier. Any reason you can't use the same make/model? Is it an availability issue? If so, you might consider the repair instead of replace.

2) If you go with a different cartridge filter, just make sure it has more than a single cartridge (i.e. >>225 sq-ft). This is paramount with a pool that closes for the winter as the opening will require frequent cleanings with a small cartridge. This is one reason why many PBs recommend sand for pools that close over the winter. But a very large cartridge filter isn't that bad either as long as you have a filter bypass put in so during the first stages of cleanup, you can bypass the filter.

3) A large cartridge filter makes the pump size moot as they are usually over 125 GPM which that pump will not do on standard 2" plumbing. However, if you want to save on energy, there is no reason you couldn't downsize the pump impeller. I have 425 sq-ft cartrdige filter and I used to have a 1/2 HP pump and it work just fine. No issues.

4) If you can't repair your current filter and you cannot get a large cartridge, then a large sand filter is the next best thing. Depending on the max flow rate, an impeller change may be necessary. You really don't want to exceed the maximum flow rate of a sand filter.

1poolman1 said:

Ferretbone, you are one of the very few people I know of that understands what happens when a pump is downsized.

Your question about 63gpm means you know that is 7 fps in 2" plumbing. 63? C'mon? At first I thought that was a legit question.

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Thank you Sir

"Your question about 63gpm means you know that is 7 fps in 2" plumbing. 63? "

I think I rest my case.

Case closed. Still trouble with the curve.

Can you enhance your signature a bit, so folks don't have to go and hunt through pages of posts to figure out what kind of pool you have? Something like my signature answers all the questions your fellow helpers might ask, including the type of test kit(s) you have.

The short answer is yes, emptying a pool always comes with risks. Concrete pools can blister and even lift out of the ground. Vinyl liners can float off the bottom. Fiberglass pools are not immune either. The water is an important structural element of your pool. My goal is to never empty my pool again, and I certainly wouldn't do it just to clear algae, which can be handled with the SLAM process and a little elbow grease.

Besides, even with all new water, you'll still have to SLAM anyway, to clear algae that is stuck to the walls or lurking in other areas of your pool and its systems.

With high water tables, there is always a chance of damage to the pool. Do you know if your pool has a hydrostatic valve in the bottom of the pool?

But that is a waste of water. You are better off vacuuming to waste to get rid of most of the large debris and then add the chlorine to kill the algae. During this first step, bypassing the filter will prevent quick clogging. Once the algae is dead and on the bottom, once again vacuum to waste, then start filtering.