Sump return pump (constant vs adjustable).

[dreamcatcherr9]

With controllable pumps on the market (with speed adjustments and feed modes); vs a return pump that is more standard....

I would think a controllable pump would be desired, to adjust flow as needed (but wouldn’t a gate valve do that during initial set up?).

But set on a “feed mode”, or shut off, wouldn’t the sump begin to overflow from the water still siphoning from display tank??

Forgive the ignorant question, trying to learn.

 

[splitting_lanes]

The tank stops draining to the sump once you hit the siphon break point, before the sump fills up

 

[dreamcatcherr9]

Please educate me more! I have no experience with sumps. “Siphon break point”? If I am doing a water change (or draining a tank) and I start a siphon, it doesn’t stop until I stop it or there is no more water in tank (or it passes the inlet line of tubing).

I was planning on a hang on overflow box on a non drilled tank. But even thinking about a pre drilled tank (that is drilled from bottom of tank), I can’t visualize the siphon stoping.

I am probably confused; help please!

 

[sp1187]

if you can afford the DC, I'd recommend getting it. you can control a pumps flow some what with a gate valve, but I've always read it's hard on a pump restricting the flow it's trying to pump out.

 

[DarthSimon]

A gate valve can be used to shut the water down, and possibly disconnect your pvc plumbing via unions.
As far using a variable speed return pump, it's a good idea to keep your main return constant speed. For one, fluctuating speeds will make your water line in sump go up and down. This will raise havoc with your Auto Top Off, making it fill and not fill too often. Also your Protein Skimmer needs to be a steady consistent level. You will never dial in a skimmer if it's water line varies.

 

[dreamcatcherr9]

Thank you. As you can see, I am trying to research. Still not understand how your sump doesn’t overflow?

In general, it is possible to have to small of a sump??

 

[DarthSimon]

Your display tank will have an over flow box where the water rises too, then falls down to your sump. When you shut off the return pump, the water level in your tank lowers down to the over flow box bottom line, and rest of water falls down to sump. Your sump should be maybe half filled with water. It will rise maybe an inch when you shut your return off......

As far as sump or tank over flowing, it cant, unless your drain going back down to sump got totally blocked.

 

[dreamcatcherr9]

Now things are coming together! That also explains how the overflow box works (in general). I was having trouble wrapping my imagination around it (it looked like it would be right at water line, so how could water siphon out). It’s starting to make more sense.
Thank you so much for your time and experience.

 

[Dragon52]

Here's a Pic of my overflow. The darker/smaller piece is inside the tank & the lighter part is outside. If you look at the inside part you'll see slots at the top. When the return pump is turned off the water in the tank drops to bottom of the slots & no further. That's why the sump doesn't fill up. I also have a 1/8" hole drilled in my return line just below the water line to keep it from going into the sump that way.
Edit: I have used both types of pumps & much prefer the DC pump for adjusting flow. Eco-Tech M! is what I have on my 185gl tank.

 

[rusty hannon]

With controllable pumps on the market (with speed adjustments and feed modes); vs a return pump that is more standard....

I would think a controllable pump would be desired, to adjust flow as needed (but wouldn’t a gate valve do that during initial set up?).

But set on a “feed mode”, or shut off, wouldn’t the sump begin to overflow from the water still siphoning from display tank??

Forgive the ignorant question, trying to learn.

there is NO ignorant questions and i may b a little outdated but ive always run a constant matched to my over fiow .otherwise im like you itll cause issues like to much water or to little where you dont want it like your floop.i can see where an adjustable pump would b handy but if your overflow is dumping 300 or 600 gals an hr id want to pump the same amount back in.hope tech. hasnt left me too far behind but thats how i figured it back then n how i look at it now. hope this is helpful.R

 

[ca1ore]

I see no particularly compelling reason to use an adjustable pump on the main return … as long as you don't buy a fixed output pump that is much too large. Even if you do, it is fine to choke it back a bit with a valve. That does not damage the pump.

 

[Greg P]

My return lines end in locline with the nozzles partly out of the water. When the power to the return pump is off, the lines immediately stop backflowing. This is my siphon break. I didn't go with the idea of drilling a small hole as that can clog up or spray water where I wouldn't want it.
I also use a true union check valve on my return at the pump. It stops backflow but I only use it to stop water splashing out the nozzles when I turn the pump power back on.
Having the return lines completely drain means there's all that air to be pumped back to the tank and I found it made a mess until all the air was cleared out.

I thought about a DC pump but my Eheim 1262 is quiet enough for me so I'll stick with it.
My return pump is AC and sized to my 75g tank running full out with no valve to choke it back. It's been running 8 years now without issue with proper cleaning.

 

[coreytrv]

I see no particularly compelling reason to use an adjustable pump on the main return … as long as you don't buy a fixed output pump that is much too large. Even if you do, it is fine to choke it back a bit with a valve. That does not damage the pump.

I'm at this cross roads now, trying to evaluate the size pump I need to pair with my overflow, and am having trouble with the calculations. Made the first mistake of buying a pump that I think is much too large, and now that I have so many practical unknowns, I think I need to deploy a variable speed pump in the field to find out what works for this tank.

Tank is a 72" tall x 43" x 44" tank.
That means approximately 5.7 gallons per inch of DT volume.

The pump I originally bought is an MRC-MP6100 which does 4,440 gph @ 12' of head.
That means @ 5.7 gallons / inch x 2" = 11.4 gallons, 74GPM pump / 11.4GPM = 6.5x per minute.

This comes out to the entire top 2" of the tank's volume running over the overflow every 10 seconds.

That seems like a vortex up there. But I don't actually know what volume would work from a practical perspective.

Here I think a variable speed pumps gives me the flexibility to play with flow, and once I get a value that works, go with that.

 

[Snoopy 67]

Generally speaking, a sump only runs about 1/2 full.
This allows for "drain down" of water from the tank before a siphon break stops the flow.
IF there is not enough room for the water that drains you have to lift the return line higher in the water column or drill a hole in the return line facing downward to force a siphon break

 

[KStatefan]

I do not see any benefit of anymore then 3-5x for return pump flow.

Does that picture show your drain going into the ceiling?

 

[coreytrv]

I do not see any benefit of anymore then 3-5x for return pump flow.

Does that picture show your drain going into the ceiling?

Yes, the pink line is the drain line.

 

[PharmrJohn]

I do not see any benefit of anymore then 3-5x for return pump flow.

Does that picture show your drain going into the ceiling?

Agreed. Even going down to 2x is acceptable. It's the flow within the tank that is of most import.

 

[coreytrv]

Generally speaking, a sump only runs about 1/2 full.
This allows for "drain down" of water from the tank before a siphon break stops the flow.
IF there is not enough room for the water that drains you have to lift the return line higher in the water column or drill a hole in the return line facing downward to force a siphon break

This has been on my mind...I don't want the siphon to break in the event there's a power outage, then power comes back on, siphon broken, and I have a flood.

Raising a tank in the garage to the same height could be done, but would be a bit more complex. I have that potential drawing shown below:

Have you ever heard of someone using a foot valve on the siphon INLET, when pressure decreases (due to lowering water level), it snaps shut, to prevent air getting in and breaking the siphon?