COR 20 1% Min still to much?

[Member No 1]

I've search, read, repeated.... but not of the threads pertain to my question.

COR 20, set with the IQ Level set to 1%Min 70% Max.

Fallback OFF
tdata 00:00:00,0,0,100,0,0,0,0,0,0,0,0,0,0
If COR-LO OPEN Then 50
If OPT-LO CLOSED Then ON
If Power Apex Off 001 Then COR_SLOW
If FeedA 000 Then 1
If FeedB 000 Then 1
If FeedC 000 Then 1

Plumbing as follows:
COR to "T" 1-1/4"
"T" reduces to 1"
Left - 1" Flow meter ->1" gate valve -> return over left rear.
Right - 1" true ball valve -> UV -> 1" Flow meter -> 1" gate valve -> return over right rear

With the COR running at a correct MAX of 100% and the UV gate valve completely open
and the left return throttled back via the gate valve, to direct most of the flow thru the UV,
I am flowing about 600 gph thru the UV and 360 gph thru the left return for a total of
around 960 gph. This is perfect for my sump, and I prefer a slower turnover anyway.
The COR is running ~ 2500 RPM

During Feed mode, the COR slows to 1% and flows reduce to ~97 and 117 gph respectively.
COR Speed is ~ 1525 RPM.

However, this is way above the "Stall" level of the water return, and a lot is still going thru the
overflows.
So is there any other way to slow the COR down so the water in the return is "held" vs flowing?
If 70% (corrected) = the pump running at 2500 rpm and 1% is 1525 rpm, based on rpm's that only a 39%
reduction in speed.

I can't slow the MAX IQ or I lose my required gph UV/Sump flow, and if I increase the COR MAX IQ
and control the flow with the gate valves, the matter only gets worse.

So bottom line, what's the slowest (rpm) the COR can run?

Sump plumbing for reference.

Sump Plumbing.png

[zombie]

The rpm is dependent on head. The only way to reduce what speed the pump runs at a given percentage is to restrict the flow to add more head

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[Member No 1]

So setting the COR to a IQ MAX of say 80% and adjusting the gate valves to obtain my desired flow rates, this would reduce
the output at 1%. Correct?

If so I shall try.

[XLOR8T]

I tried to create a stall by adding a valve to run water into the sump (recirculate essentially) and I had to have it wide open to create a stall. Which ate quiet a bit of flow but if your max is at 70% then you may be able to make it work. Especially when the flow is low enough water will take the path of least resistance and go out first t and valve instead of pushing through the path to return of DT.






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[Member No 1]

So after changing the IQ Max level to 80%, as expected the total flow increased.
I closed both gate valves to reduce the flow to my desired flow rate (I even reduced it lower than before) for a total of
900 gph (600 UV, 300 Return) in order to induce head pressure.
The COR is now running ~ 2600-2620 rpm were before at 70% it was ~2500rpm. Power consumption is up to.
Activate FEED mode, COR Min still set to 1%, COR slows to ~1600 rpm, were as before it was ~ 1525 rpm.
Flow now at 1% is ~110 & 130 gpm. Before at it was ~97 & 117 gpm.

So durning FEED mode it's flowing MORE at 1% than before. So inducing more head pressure does not reduce
the flow at 1%

Either way you look at it, if the COR flows 900 gph at 100% (corrected) then at 1% it should flow 9 gph.
I understand the reduction is not a direct linear of % to gph, but at 1% it's flowing ~230 gph.

No matter what you do, the COR just does not run slow enough to "Stall" the water in the return.

[zombie]

That I dont understand since that appears to defy the laws of physics. I would be interested to see if running the same test at 100% and adding more head with the gate valve would continue the pattern because I can't grasp how that is even possible. Something else has to be going on there that isn't being accounted for.

Flow rate is not linear with percent because of the way frictional and minor head loss works (higher speed introduces more friction, when in turn lowers the speed until it reaches equilibrium). It does appear though that the 1% for the cor pumps is heavily offset in what appears to be a means to prevent stalls (probably to reduce warranty issues).

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[boozeman27]

I too am looking for answers to this. I guess my expectation was wrong in thinking that 1% would be able to stall and hold the water as it was described by Neptune. I tried messing with this when I first got the Cor-20 and I still got a very noisy, gurgling down (albeit a trickle, just a noisy trickle) the overflow. I couldn’t stand all the noise of the trickle during every feeding or maintenance session. I was used to silence when it just shut off. I gave up and programmed it to 0% (off) like before when I was using the L1.

51D97E73-FC1A-4B8E-A3FF-D908F8F8AD2A.jpg