Reeflo Cavitation issue

[Feet4Fish]

So I am getting cavitation with my Reeflo pump. Figured out the reason is because I have a 1 1/2” inflow and outflow but about three feet above the tank I have a T which branches into 1 1/2” for my big display and 1” for a much smaller display. So I am asking the pump to spit out 2 1/2” of water. I have reached out to Reeflo to hear their suggestions. All I can find is an email and I haven’t heard back yet. Anyone have a phone number for them?

so my question is....

1. Will bumping the inflo to 2”do any good?

2. Run a deuce are’s pump for the smaller tank. So basically run two return off same sump to two different tanks!

 

[Feet4Fish]

Bump

 

[DCR]

Are you sure it is cavitation or just air being ingested into the pump via a vortex?

Pump cavitation is caused by low head at the pump inlet. Centrifugal pumps require a certain amount of positive pressure above the vapor pressure of the fluid to prevent flashing inside the pump (cavitation) The greater the flow rate, the more suction head that is required by the pump. You either have to reduce the flow through the pump, raise the water level in the sump, or reduce the pressure drop in the suction. Raising the water level is probably not going to be practical unless it is very low. Debottlenecking the suction line will (e.g. going to 2') will normally work, but if it is a high head pump (i.e. pressure rated) and you are just running it off the end of the curve (with high flow and low head), you may have to reduce the flow rate. Just eliminating the 1' take-off does not guarantee that you will solve the problem, although it will help. Throttling back either line will help and if you can test it so much the better.

A 1-1/2" suction line is pretty generous for most aquariums, so you would need to be really moving a lot of water to overload it. I would expect that it would carry anything around 1500-1800 gph and under - unless it is very long and contorted. Make sure you do not have any other unnecessary restrictions. On the other hand, suction lines are generally at least 1 or 2 pipe sizes larger than the discharge for this reason.

 

[ca1ore]

One way to check to see if it is actually cavitating is to choke the output way down and see if the problem resolves (it should). If not, you’re sucking air from somewhere.

 

[Feet4Fish]

Thanks guys . Will try that in a little while and post an update.

 

[vetteguy53081]

I think air being sucked in

 

[Feet4Fish]

I am wondering. I will try to dial back the pump A lot and see if it that works as @ca1ore suggested. If not I will take down the plumbing from the sump to the pump and redo it.

I think air being sucked in

 

[Feet4Fish]

So...it is cavitation. I have run it for about 90 minutes with the 1" line of the Tee valved completely off and no bubbles at all. Just valved open the 1" line about 25% and bubbles! So the question is can I increase inflow pipe diameter to make it balance out? The other idea is just to use a separate dedicated pump for the 1" line (this is easy as I already have the pump). What two you guys think?

 

[DCR]

Which Reeflo pump are you using? I think there is a very high probability the 2" suction line will solve the problem, but it would help to know which pump you have. Keep in mind the upgrade would include the bulkhead connection to the sump.

 

[Feet4Fish]

Big boy. A Tigershark

Which Reeflo pump are you using? I think there is a very high probability the 2" suction line will solve the problem, but it would help to know which pump you have. Keep in mind the upgrade would include the bulkhead connection to the sump.

 

[WVNed]

I stole these words from the internet
Two types of cavitation are possible: suction and discharge.

In the case of suction cavitation, low-pressure or high-vacuum conditions “starve” the pump of incoming liquid, resulting in low flow.

Discharge cavitation happens when a pump’s discharge pressure is inordinately high — In other words, the pump is running at less than 10 percent of its best efficiency point (BEP).

This is from an industrial pump website but it is kind of common knowledge. Cavitation comes when the blades of a pump spin in the liquid but aren't moving it. A vacuum is formed behind the blades and bubbles are sucked out of the liquid

I don't see how what you are doing that is causing the bubbles fits either one of these cases.
Opening a valve should reduce the outlet pressure, not raise it.

If I were to try and fix this I would try to reduce any intake restrictions.

I don't see how what you are doing is causing cavitation.

 

[Feet4Fish]

I notice the bubbling stopped when I shut off the 1” feed to my second, smaller tank. This left the outflow at only the 1 1/2” line. The inflow and outflow at that point were 1:1.

as fair as inflow restrictions not sure what would be causing it. Plumbing goes from bulkhead to gate valve (wide open) to union to intake. Total run is about 14 inches.

I stole these words from the internet
Two types of cavitation are possible: suction and discharge.

In the case of suction cavitation, low-pressure or high-vacuum conditions “starve” the pump of incoming liquid, resulting in low flow.

Discharge cavitation happens when a pump’s discharge pressure is inordinately high — In other words, the pump is running at less than 10 percent of its best efficiency point (BEP).

This is from an industrial pump website but it is kind of common knowledge. Cavitation comes when the blades of a pump spin in the liquid but aren't moving it. A vacuum is formed behind the blades and bubbles are sucked out of the liquid

I don't see how what you are doing that is causing the bubbles fits either one of these cases.
Opening a valve should reduce the outlet pressure, not raise it.

If I were to try and fix this I would try to reduce any intake restrictions.

I don't see how what you are doing is causing cavitation.

 

[WVNed]

The pump is built with 1:1 inlet/outlet dimension. Why do you think this is relevant? Pumps are often used to feed multiple points that turn on and off. The pump would cavitate when you turn them all off, not on.
That is the opposite of what you are saying.

Do you have a 90 screwed into the pump inlet?

To have a well-developed flow pattern, pump manufacturer's manuals recommend about (10 diameters?) of straight pipe run upstream of the pump inlet flange.

 

[Feet4Fish]

By 10 diameters are you saying 15 inches (1.5 x 10) ? No elbows from sump to pump inlet. Straight shot.

as far as your first point....I tried the suggestion thata few people made and valved back the outflow. That did get rid of the bubbles. This is my first time dealing with this issue so I am welcoming any and all advice and education. Thanks!

The pump is built with 1:1 inlet/outlet dimension. Why do you think this is relevant? Pumps are often used to feed multiple points that turn on and off. The pump would cavitate when you turn them all off, not on.
That is the opposite of what you are saying.

Do you have a 90 screwed into the pump inlet?

To have a well-developed flow pattern, pump manufacturer's manuals recommend about (10 diameters?) of straight pipe run upstream of the pump inlet flange.

 

[WVNed]

I am reaching. Cavitation is cause by a few common things but you don't seem to have any of them.
The 10 diameters is a common design point I found.
Most people on here, at least the ones that bother to answer posts don't have a pump that big. I don't either.
Take a look at this and see which fits your situation
https://www.dultmeier.com/videos/pump-cavitation-explanation.php

 

[WVNed]

My last point would be when the pump is putting out bubbles does it become noisy? Tiny explosions of bubbles imploding can usually be heard.

Could you be sucking in bubbles from your sump. When you open all the valves you increase the flow through the pump and it will draw in water from farther away.
That was my last guess.

 

[vetteguy53081]

My last point would be when the pump is putting out bubbles does it become noisy? Tiny explosions of bubbles imploding can usually be heard.

Could you be sucking in bubbles from your sump. When you open all the valves you increase the flow through the pump and it will draw in water from farther away.
That was my last guess.

That's what Ive been thinking all along as I experienced the same

 

[Feet4Fish]

So everyone particularly @WVNed and @vetteguy53081 please comment on the list with yes or no to each point....

1. increase inlet bulkhead to 2”

2. Make straight run of pipe to inlet at least 15“

3. Keep T at three feet above outlet with 1” and 1 1/2” outflows

4. Keep outflow at 100% or valve it back

Current set up is 1 1/2” bulkhead with 12-14” straight pipe fun. 1 1/2” outlet to T about 3’ above with 1 and 1 1/2” outflows. 1” out flow closed off and 1 1/2” outflow wide open. No bubbles now for abut 14 hours.

I really appreciate all the help and I am learning a ton.

@WVNed. I will watch that video in a bit . At work right now.

 

[Feet4Fish]

Reeflo has gotten back with me and they also believe it is cavitation from not giving it enough incoming water for the outflow the plumbing is demanding.

 

[WVNed]

You have what I would have built. A pump with 1.5 inch inlet/outlet should work fine with 1.5 inch plumbing I would think unless one of the fittings is restrictive. I would do what they say.

Water flows from higher pressure to lower pressure. The outlet plumbing cant make the pump flow more than it was designed to do. If you put a 3 inch pipe on the pump the volume coming out of it wouldn't go up magically.

but
I am guessing now
That is a high pressure pump. The flow through the body may be too much for the inlet/outlet size of the pump body with no restriction on the outlet.

So you could put a valve on the outlet so you can throttle the pump a bit and back up some pressure. That seems like a band aid to me but I think it would work.

I think your pump is to big. Not a bad problem to have.