Is this an optimum return setup for a 90 gallon?

[islandkoa]

I recently purchased a pre-plumbed 90 gallon acrylic tank (with sump/stand) from someone. I noticed that the return line went up through the bottom, back (in the back plumbing housing area). The return pipe goes up near the graded overflow, does a 180 degree turn, goes back down, then goes out of the housing about 2" from the bottom where it is split. Each split runs along the back and has multiple holes pointed forward and up along the PVC. It also has two holes near the highest point below the 90 degree elbow at the top (to break the vacuum if loss of power) that ineffectively sends some return flow back down the drain to the sump. This coupled with the added plumbing length and multiple 90 degree elbows currently required to reach the top then bottom of the tank, seem like an unnecessary attenuation of the return flow.
I think that I should modify the return plumbing to have it exit near the water surface (like most others). Maybe for curiousity fulfillment, I'll measure the flow rate with this current set up (I have to clean the tank anyway) and compare it to the rate after the modification. Another option is to just leave it alone, trust the system won't overflow in the event of a power loss and live with the attenuated return turnover.
Any thoughts on this before I flip a coin?

 

[sweatervest13]

The pics did not come through.
Are you saying that the siphon break (should be a little hole drilled in the underside of the return plumbing within the tank, the hole should point down towards the water) is making water flow back into the sump tank??? Or it is just back siphoning through (within) the return PVC?? Back siphoning is fine as long as that siphon break kicks in to stop the back siphoning. But it for some reason water is getting back into the sump after the siphon breaks, then you have an issue.
Some return plumbing will have multiple nozzles off the main return pipe once inside the tank (to get ******** flow on the top, middle, and bottom of the tank. Some will just have one or two nozzles towards the top. The more turns that the plumbing makes the more restricted the flow will be. So obviously the less turns the better. But once in the tank if the flow is split between 1,2, or 3 nozzles it should have the same effect it would just be divided by the number of return nozzles.
I have a return that is split into 3 different return nozzles (top, middle and bottom), but I can shut down any of the three. If one is shut down the flow will still be the same just split between the remaining two, or the single return nozzle.
If you cleaned up the plumping to have less restrictions (turns) that should increase the amount of flow.
But to tell you the truth, the flow from your return pump should not be used as internal flow. That should be provided by powerheads or a Closed Loop system.
I bet the pics you tried to post would help make sense a bit more.

 

[eric b 125]

Pics would help.

 

[islandkoa]

My pictures were previously uploaded incorrectly. I think I will go with my first option to see what the flow rate will be and make a decision at that point whether or not to change the plumbing. I will have my wp40 and possibly my koralia and tunze if needed for internal flow. I am just concerned about water turnover at this point. I have never come across a rule of thumb regarding turnover recommendations, probably because of all the factors: bio-load, live rock, skimmer, refugium, sump size/time, etc.

 

[eric b 125]

That's interesting. It's a nice idea to have the return come out at the bottom like that, but I see a few problems. The first one being that should the siphon break get clogged it will completely drain your tank. Another thing is if you ever need to service that part of the plumbing you will have to tear the entire tank apart. Also, in the event of a power outage, or even during water changes when you power down the return pump, you run the risk of sucking sand into the return plumbing and possibly into your return pump before the siphon breaks.
As far as the amount of flow going through the sump: I agree with sweatervest in that it shouldn't be used as internal tank flow. I use a mag18 as my return, but I feed a refugium from it and I also use a SCWD which adds a good bit of head pressure. I think 10X turnover is a good rule of thumb.

 

[islandkoa]

Focusing on the flow rate, I never even considered the real possibility of sand/detritus getting sucked up into the return line. Perhaps this setup initially had a canister filter vice sump which would have negated a reverse siphon threat. I'll modify this by plugging the hole below, removing the excess plumbing, and placing the return near the surface and look into the SCWD (which I've considered in the past). Thanks for the different perspectives.

 

[2quills]

Wondering if that might have initially been set up as a bare bottom tank with the rocks elevated on the rods. Definitely can't see running it that way with a sand bed. Sounds like you're on track to better ideas.

 

[islandkoa]

Quote:
Originally Posted by 2Quills http:///t/396238/is-this-an-optimum-return-setup-for-a-90-gallon#post_3529855
Wondering if that might have initially been set up as a bare bottom tank with the rocks elevated on the rods. Definitely can't see running it that way with a sand bed. Sounds like you're on track to better ideas.
You're correct. There is a "rock rack" with removable rods that was used without a sand bed according to the previous owner. Not sure if his choice of not having a sand bed was because of the plumbing or not. I've never heard of such a concept (no sand bed) especially with no refugium in the system. Maybe it's a good idea. . .don't know but I'm going to stick with a sand bed and modify the plumbing.

 

[2quills]

Quote:
Originally Posted by Islandkoa http:///t/396238/is-this-an-optimum-return-setup-for-a-90-gallon#post_3529857
You're correct. There is a "rock rack" with removable rods that was used without a sand bed according to the previous owner. Not sure if his choice of not having a sand bed was because of the plumbing or not. I've never heard of such a concept (no sand bed) especially with no refugium in the system. Maybe it's a good idea. . .don't know but I'm going to stick with a sand bed and modify the plumbing.
I think the bare bottom tanks became moderately popular with those running mostly SPS dominant systems for a little while there. They seem less common these days. I prefer a more natural look with sand, myself and the extra bio diversity potential. There are pro's and con's for both sides.

 

[sweatervest13]

I would have never thought to plumb a return that way but if it worked for the previous owner than...
I think you are going down the right path now. Plug that hole and install a traditional return.
What kind of plans do you have for this 90g??

 

[islandkoa]

The plumbing was professionally done a few years ago by a saltwater tank business just north of Seattle. I may make the drive up there to see their products and discuss this setup. . .perhaps see some examples of such setups. Not sure how well it worked for the previous owner as the system was secured (Navy term), emptied, and sitting in the basement. The large sump has a movable acrylic 3-drawer wet/dry "cabinet" that I will probably replace with a refugium section. Anyway, I will have a SPS/LPS and selective soft coral reef setup using the Precision Marine Bullet 2 protein skimmer and refugium sump with berlin sock for filtration and my two 120w LED fixtures for light. I might consider an additional HOB refugium that's currently collecting dust in my aquarium shed.