The FPI C50 is designed for a 1 hp pump. Bigger wont filter properly, it will bypass as I recall it.
Old inground spa and pump
- Thread starter greeensky
- Start date
- May 3, 2007
- 16,945
- Pool Size
- 20000
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- Hayward Aqua Rite (T-15)
You really can't go by the HP of the pump to determine if it is suitable for a particular filter. HP alone does not determine the flow rate and filters are generally spec by flow rate, not pump HP. For cartridge filters, maximum flow rate is generally specified at 1/sq-ft which is 50 GPM or 190L/min. This isn't the same housing but it uses the same filter:
Waterco Commandomatic TCF Series C50 Cartridge Filter Housing Top Loading
The Waterco TCF Commandomatic Trimline cartridge filters are compact, economical filters designed to effectively filter out suspended solids from a range of process streams in water treatment related applications. Large range of specialty filtration equipment supplied across Australia by Parkway...
pwnps.com
The Speck 90/350 has the following head curve:
Taking into account the head loss of the plumbing, spa jets, filter and heater, the most likely operating point would be 167 l/min @ 11m of head so below the maximum flow rate of the filter.
I worked for FPI. This filter was originally designed to match their 1 hp at the time.
- May 3, 2007
- 16,945
- Pool Size
- 20000
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- Hayward Aqua Rite (T-15)
While it might have been matched to their 1 HP pump, it does not mean it will work for every 1 HP pump nor does it mean it will not work for a pump that is larger. The operating point of the pump matters.
th
thanks, also on the pump usage, i think to maintain temperature will need to run both the heater and the pump more often then just that. so in the long term it may pay off getting a pump under 1hp. for now im going to test 1.25hp later this evening...
It is not matched to any pump larger. Generally, 1 hp pumps will all flow similarly within physical limits. It won't matter enough to justify a different filter whether the pump does 167 or 197 lpm on a domestic setting. Sorry for using ROT for this, but it's too long back to be specific.
- May 3, 2007
- 16,945
- Pool Size
- 20000
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- Hayward Aqua Rite (T-15)
There can be a very LARGE difference between pumps with the same HP rating. While there is some correlation between a motor HP rating and the attached pump's head curve, you really cannot deduce one from other.
Below is a comparison of pump models I did many years ago. While there is a general trend of higher flow rates for higher HP there are cases where the opposite is also true.
The 2 HP Optiflo on Curve-C plumbing produces 67 GPM while a 2 HP TriStar will produce 85 GPM, a 27% difference. Not trivial.
It is far too simplistic to use only the pump HP to determine the appropriate matching.
Here is a different way to look at the data. It shows motor THP vs GPM for Curve-C for a much larger dataset.
Pump Database
PumpData Model,Manufacture,RPM,GPMb,GPMa,GPMc,WATTb,WATTa,WATTc,RPMl,GPMbl,GPMal,GPMcl,WATTbl,WATTal,WATTcl,THP,NHP,HHP,WEFa Energy Advantage Variable EAPVS2,Advanced,3450,40.00,67.00,88.00,1813.00,2114.00,2355.00,1725.00,20.00,33.50,44.00,274.75,312.38,342.50,3.45,3.00,1.41,6.29 Quiet Flo Varia...
You can see cases where the flow rate of higher THP pumps is actually lower than some with lower THP by a very significant amount.
does it mean that above 1hp generally is not recommended. or if unsure, beterr go slightly less ie .75hp? though 1.25hp should not provide too much more pressure i would hope so. The Badu Spec Super 90/350 has 350l/m flow and has been removed from a similar old inground spa togehter with the other FPI filter so this suggests it should be ok..
Last edited:
- May 3, 2007
- 16,945
- Pool Size
- 20000
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- Hayward Aqua Rite (T-15)
As I mentioned in my last post, it is mistake to go by nameplate and/or THP to determine if the pump a good for a filter or not. The flow rate ranges for various pumps are much too large to do that reliably. You really need to look at a pump's head curve and plot the plumbing curve over it to find the operating point. This is going to be the most accurate method of predicting operating points. To illustrate this point, here is the head curve of the Badu overlaid with a Hayward Tristar 1/2 HP pump:
Note that the two pumps have nearly identical head curves but the nameplate HP is vastly different (1/2 HP vs 1.25 HP). If you have some other pumps in mind, post the make/model and we can look at the head curves in more detail so you can make the correct choice.
Based upon the information you provided, the Badu flow rate should be below the filter maximum. That is a fairly weak 1.25 HP pump with a low head curve. So it should be fine to just try out and see if it produces enough flow rate for the spa jets. Also, post back the filter pressure after installing the pump and I can refine the estimate.
However, long term, I would suggest a larger filter for less frequent cleanings and less concern about exceeding flow rates.
You mentioned before that the 1.5 HP was too strong. Were the jets too strong or was it something else?
Badu spec is not a good match. These are a later model pump with a large flow model. I would be looking for a flow of about 150-200 lpm and no higher at about 6 metres on the pump curve.
I wouldnt bother with VSD based pumps.