Questions about adding a sump to an existing display.

[DJasak]

I currently have a 45 gallon tank that I want to add a 10 gallon sump to. I don't want to have to break the tank down to drill the glass, so I was thinking about using a powerhead to pump the water up over the rim of my tank and down into the sump and then use another one to pump the water from my sump back up to the display. Is there any reason why this shouldn't be done? Probably a stupid question but I just haven't seen anybody else do this or talk about it so I was curious if there was a reason why. If I do it this way I want to add a couple shut off valves so I can control the flow and I was going to put a sponge over the intake of the first pump that would send water down to the sump. Also what type of pvc primer and glue is recommended to use on our aquariums? And is there any type of aquarium safe paint I can use to paint the pvc black that'll be against the back of my display? Any recommendations on what type of pumps I should use?

 

[Dkuhlmann]

You need something like this HOB overflow box, then also add a return pump. Personally I would go more than a 10 gal sump. You can get a 20 gal for a sump from Petco $ per gal sale that they have quite often. This way you'll have room for extra rock for filtration, a place to put a skimmer and your heater.

http://www.saltwateraquarium.com/pf-300-overflow-box-eshopps/?gclid=CND9gcG_s8oCFQqtaQodsigP5Q

 

[pyithar]

you can use a hob overflow box for the siphon. you'll need only one pump for return. i'd use a 20g sump instead. 10g is a bit small.

 

[thegrun]

No one does it because it is impossible to balance out the flow between two pumps, even with gate valves to adjust the flow one pump or the other will get debris inside it or calcium deposits will slow one pump down, the end result is always a flood.

 

[sde1500]

As others have said, use the HOB overflow. I have one on my tank now from Eshopps. It works well, isn't silent but a little fiddling with it and it's pretty quiet. Also starts right back up every time after I turn the pump off. I tested it a ton and never had an issue. Just need to make sure you have enough flow through to keep bubbles from forming in the siphon hose.

 

[SaintJimmy]

I've been considering adding a sump to my setup as well, and the PF-300 looks like it'll work fine as far as getting water from the tank to the sump. Now, forgive me if this is a dumb question. I'm new to marine aquariums and I don't have an extensive plumbing background... but doesn't the return pump need to match the overflow intake? I'm assuming you'd use a submersible pump to return the water. If water is coming into the tank faster than water is leaving the tank via the overflow siphon, then one of 2 things is going to happen... 1.) You're going to overflow your tank, or 2.) your submersible pump is going to run its compartment in the sump dry. Neither of those are desirable results.

How would you go about achieving balance there? Or is there something I'm missing as far as plumbing knowledge goes that would make this a non-issue?

 

[Dkuhlmann]

Max flow on siphon (which is how these work) of a 1" hole is something like 2000 gph if I remember right. You're not going to put too much of a pump using this HOB unit on most tanks.

 

[jsspallina]

Why do you want a Sump

 

[Mr.Tan]

Why do you want a Sump

extra water volume, place to hide equipment, ability to have a refugium for some more nutrient control.




OP: if at all possible, i'd try for a larger sump... Coming from someone with a 10g used for one, i wish i would have modified my stand to accommodate at least a 20g tank

 

[Irishman360]

Also what type of pvc primer and glue is recommended to use on our aquariums? And is there any type of aquarium safe paint I can use to paint the pvc black that'll be against the back of my display? Any recommendations on what type of pumps I should use?

I used the hot glue/quick set glue. Let it set and dry for 12+ hrs and then run a lot of water through it. I'm sure there are stores on line that sell them or as your LFS.

 

[CStrickland]

Max flow on siphon (which is how these work) of a 1" hole is something like 2000 gph if I remember right. You're not going to put too much of a pump using this HOB unit on most tanks.

It's not a full siphon. The pf 300 maxes at 300gph, the pf 800 at 800 gph.

 

[sde1500]

I run the pf800 and can say for a fact it's not handling 800/hr. I have a couple 90s in the plumbing so maybe that's the difference but it can handle much less than that. Now just put a valve on the return line to throttle flow and you're fine.

 

[CStrickland]

How would you go about achieving balance there? Or is there something I'm missing as far as plumbing knowledge goes that would make this a non-issue?

The way the hob works is the utube connects the inside and outside boxes. Water will flow between them to achieve the same level on both sides (siphon). So as you pump water into the DT, the inside box level goes up, and water flows into the outside box to even them out, and down the drain to the sump.

In a sense, it is self balancing because the siphon isn't pulling water out of the tank, it's just catching overflow.

It's not as complicated as it sounds, it's just sort of hard to describe. You'll get it when you see it. This might help to: http://www.melevsreef.com/node/710 there's an animation of an overflow, and links to tons of other good sump info

 

[Dkuhlmann]

It's not a full siphon. The pf 300 maxes at 300gph, the pf 800 at 800 gph.

Then why do all of them have 1" bulkheads? I'm pretty sure that the siphon capacity of a 1" bulkhead is around what I said before 2000 gph, well I was off... it's 1621 gph at a 12' head.

PF - 300, PF - 800, PF - 1000, and PF - 1200 have 1 " bulkheads

The difference in all of those I just listed is the size of the overflow box, not the bulkhead. But you're correct the 300 is 300 gph. So any of those listed should have a return pump no more than the siphoning drain capacity for them to work correctly.

Here read this link
http://www.reefcentral.com/forums/showthread.php?t=1814606

 

[SaintJimmy]

Thanks for the info, guys. Great information from those links you provided. Much thanks for those.

So if the overflow box maxes at 300gph, I need a pump slightly stronger than that to account for head loss depending on the distance from the pump back to the top of my display tank.

I also like the idea of splitting the return and using a ball valve to divert some of the return flow back into the sump. There's an example at CStrickland's link. Someone had mentioned adding a valve to control the flow, but my thought then was that doing that would put pressure on the pump. That setup seems to solve that problem.

My only reservation now is what if the siphon breaks? Are these HOB overflow boxes fairly reliable? If I turn the return pump off and back on does the siphon resume?

 

[CStrickland]

Then why do all of them have 1" bulkheads?
[...]
Here read this link
http://www.reefcentral.com/forums/showthread.php?t=1814606

That links to a discussion of drain capacity using full siphon drains, the lack of air in the pipes allows them to run much much much faster. These hob's are not full siphon so they do not move nearly as much water.

Iirc the max flow on a 1" drain that isn't doing anything to keep out air is ~600 gph. That might be conservative, like a realistic safe flow as opposed to the most you could ever run. I guess the box size, utube width, and height differential between the inner and outer box, as well as elbows and length of drop to the sump, and manufacturer optimism would all affect the capacity of the drain. Note that the 1200 is a dual drain, so 600 each makes sense.


NOTE: this might be confusing for new members. We use "siphon" for two diff things in this discussion. Basically, a siphon is a pipe or tube that only has water in it.
1. These hob overflows use a siphon to pull water over the back edge of the tank, as long as no air gets in the water "wants" both ends of the tube to be equally submerged so it will pull water out of the tank as it rises above the back-side level to even things out.
2. Drain plumbing also uses siphons. If a drain is set up so that no air ever goes in the pipe, it can carry a looot more water. Something about how the air bangs around and slows the water down. So "full-siphon" drains like a beananimal can move thousands of gallons per hour through a 1" drain, but ones that let in air like a durso can only drain a few hundred per hour.

 

[CStrickland]

Thanks for the info, guys. Great information from those links you provided. Much thanks for those.

My pleasure.
Once you narrow down your pump choices you can find charts for head loss on the diff brands, as well as the reduction from diff elbows and fittings. I really love my eheim compact+ 2000, I'm sad it's too little for my new tank. It's not as awesome as the regular eheims but you can get one for like $75.

You don't need to worry about restricting the flow out of the pump. They are designed for it.

The boxes are pretty reliable unless the flow is too slow and bubbles build up in the tube like the other poster said. The ends stay under water so it's hard for the siphon to break. Some folks try to mod them with air pumps and check valves but IMO that makes it more likely to fail.

 

[sde1500]

I've turned my pump off and on a few dozen times. Sometimes left it off for a few days as the tank was cycling and I was doing plumbing work. Never an issue on restart. The box keeps both ends of the U hose submerged at all times and that's all you need to restart successfully.

 

[Dkuhlmann]

Yes that would be correct.

Thanks for the info, guys. Great information from those links you provided. Much thanks for those.

So if the overflow box maxes at 300gph, I need a pump slightly stronger than that to account for head loss depending on the distance from the pump back to the top of my display tank.

I also like the idea of splitting the return and using a ball valve to divert some of the return flow back into the sump. There's an example at CStrickland's link. Someone had mentioned adding a valve to control the flow, but my thought then was that doing that would put pressure on the pump. That setup seems to solve that problem.

My only reservation now is what if the siphon breaks? Are these HOB overflow boxes fairly reliable? If I turn the return pump off and back on does the siphon resume?

 

[Dkuhlmann]

Those boxes are governed by the box itself to limit flow from a full siphon in all sizes that use the 1" bulkhead fitting. Siphon is the only way they can work once its primed with the return pump,pumping more water than the tank itself holds causing the overflow into the little box. If the overflow box is fed by a tube that goes below the water surface to bring water over the back of the tank into the box and has no pump, how else does the water flow over the back of the tank through the tube? Siphon, and its limited by a few things, one being head height, two being diameter of the tube or hose, and three the size of the box it flows into before returning down into the sump. The return pump will be at a different section of the sump to actually pump the water back over the top of the tank in a different place. So again siphon is what makes the overflow box work in the first place. Is it capable of a full siphon, no, but it's no less a siphon and that is how it works. otherwise it would have to have a pump to pull the water over the top into the box then be pumped back up as the OP was saying originally. :lmao: I'm not even sure that makes any sense to me

I'm just trying to shed some light on how it actually works so it makes sense. But I do agree with you that those boxes have limiting factors that reduce the siphon. As pointed out by others they're not perfect by any means, so maybe getting a size or two bigger so you can have a decent amount of flow from the return would make for a situation where maybe only one powerhead is needed for the extra flow in the tank.

That links to a discussion of drain capacity using full siphon drains, the lack of air in the pipes allows them to run much much much faster. These hob's are not full siphon so they do not move nearly as much water.

Iirc the max flow on a 1" drain that isn't doing anything to keep out air is ~600 gph. That might be conservative, like a realistic safe flow as opposed to the most you could ever run. I guess the box size, utube width, and height differential between the inner and outer box, as well as elbows and length of drop to the sump, and manufacturer optimism would all affect the capacity of the drain. Note that the 1200 is a dual drain, so 600 each makes sense.


NOTE: this might be confusing for new members. We use "siphon" for two diff things in this discussion. Basically, a siphon is a pipe or tube that only has water in it.
1. These hob overflows use a siphon to pull water over the back edge of the tank, as long as no air gets in the water "wants" both ends of the tube to be equally submerged so it will pull water out of the tank as it rises above the back-side level to even things out.
2. Drain plumbing also uses siphons. If a drain is set up so that no air ever goes in the pipe, it can carry a looot more water. Something about how the air bangs around and slows the water down. So "full-siphon" drains like a beananimal can move thousands of gallons per hour through a 1" drain, but ones that let in air like a durso can only drain a few hundred per hour.