Pentair Cristal-Flo VS Pentair Sand Dollar

[durtynacho]

I'm sure this sort of thing is asked all the time on this board, so I apologize in advance. I haven't found any topics that compare these two filters specifically online, so I figured I would come here. Anyway, first I will offer some details as to why I am looking at a new filter in case there may be something I am missing about my setup that is contributing to my problems.

I currently have a 150 square foot Pentair Sta-Rite cartridge filter and a 3/4 HP pump that I hate. I think its undersized for my above ground pool (17x33 by 5FT deep and a capacity of 22,500 gallons). My pump only has good pressure for a few hours before dying down. I then have to take the filter out, which is new, and clean it. This happens even with clean water; if I was clearing a green pool I would understand the pressure dying but its not green. The filter isn't even that dirty when I take it out, so perhaps just opening the cavity and putting it back together is fixing the pressure each time. There is a little pressure bleeder thing that clogs pretty easily, I usually find that once I clean that off the pressure returns. I cannot offer any info on what my pressure actually is as the pressure reader doesn't seem to work.

My plumbing is all inch and a half. I have two skimmers and two returns, although the second skimmer and return were just added and this problem existed prior to adding them. The hose runs are between 20FT and 40FT in length. The pump is older, and probably too weak for the size pool I have.

So, I am looking at a new filter/pump combo and want to stay with Pentair, and I want to go with sand for ease of maintenance. I don't think I need the filtering power of DE or cartridge, and I want an easier filter to maintain.

The two products they seem to offer are their Cristal-Flo and Sand Dollar models. From their website, the only difference I can find are the material used to make the shell and nothing regarding the pump or plumbing (both come with 1 1/2 HP Dynomo pumps and are top plumbed).

Does anyone have experience with both or knowledge of both that can recommend one? I want to go with their 22" 250 pound model, which I believe is big enough for my pool and will filter better than a 150 SQ FT cartridge filter. Anyone agree?

Thanks so much for any advice that is offered!

 

[jblizzle]

For a pool of that size, a minimum cartridge size I would recommend is 325 sqft ... so your existing one is quite small.
The only reason for the flow to slow down is if the filter is getting clogged up ... perhaps you have algae that is not easily visible?
Sounds like at a minimum you need a new pressure gauge.

There is no reason to have a large pump or high flow rates. It just uses more electricity. That is why people are switching to 2-speed or VS pumps so they can run at lower speeds.

If you want to go sand, then I recommend a minimum of 27" diameter, that 22" is way too small.
If you want a new pump, then a 1HP 2-speed is what I would suggest, like the Powerflo Matrix. So you can run on low speed ... but that is counter to what you think your problem is.

How are you testing your water?
Can you post test results?

While your filter is undersized, symptoms you describe are more often a chemistry problem and not a filter problem.

 

[durtynacho]

I take my water up to Leslie's quite often and they test it out. Sometimes my water is a bit hard and needs acid but most of the time its fine, and it is fine as of yesterday. Yesterday my PH was 7.8, alkalinity was 200, free chlorine 4. I don't think I have any algae issues either.

If the lower pressure is sufficient then I probably don't have a problem. After cleaning the filter and turning the pump back on the return jets are pretty aggressive, almost like a hot tub jet. Then after a few hours they are less than half that strong but if that is acceptable, then so be it. Like I said, the pool stays clean, so this setup must be working. I just assumed it wasn't running efficient due to the jets slowing down after a while.

I've had the 24" sand filter recommended to me for my size pool, but I'm not surprised if that was a poor recommendation. The 22" is the biggest these two Pentair models offer so I was hoping they would be suitable for my size pool. I was also told if I go bigger than 24", I will need 2" plumbing, which I don't want to do because I just spent a lot of money on new 1.5" hoses.

 

[jblizzle]

I only got 10 words into you post and started typing. Pool store testing is notorious bad and not reliable. If you want to take control, you need to invest in one of the Recommended Test Kits.

Hardness has nothing to do with adding acid. What is the CYA? That is what determines the required FC level ... 4 might be way too low. See the FC/CYA Chart.

Have you discovered Pool School yet? Start with these:
ABCs of Water Chemistry
Recommended Pool Chemicals
How to Chlorinate Your Pool

You are getting horrible advice. The size of the filter has absolutely nothing to do with the size of the plumbing. A filter and a pump are 2 separate pieces of equipment, too often they are sold packaged (and often poorly matched) which gets people confused.

I would start looking into the chemistry. I have no explanation for the flow rate dropping beyond the filter getting clogged.

 

[durtynacho]

When I say the water is hard, I mean the alkalinity is too high. If the two are different, then I am using the terms incorrectly. But that is what I meant about my water being hard, that the alkalinity is too high sometimes.

My CYA was 80 and my FC and TC were both 15, not 4. I was looking at the chart range and not the total values earlier so I apologize for the confusion. I had just shocked the pool yesterday morning and took the test water in the afternoon, which is why the chlorine levels are really high.

Is it possible to have chemical issues and still have nice clear water?

 

[jblizzle]

Yes it is possible.