spray bar return at bottom of tank

[FishTruck]

Hi there. In my new tank I am contemplating a spray bar return at the bottom of the tank. This tank will be a room divider, view able and accessible on three sides. The goal is a moderate to gentle flow - pushing detritus to the sides of the tank... where I can see it. The tank might have substrate or be bare bottom, and the estimated flow through the 1.5 inch pipe would be about 4 thousand gph. The tank is ten feet long. This idea was popular, I think, years ago, but fell out of favor.

1. siphon break. I would put that at or above the water line. I could valve it to adjust the relative flow on top versus bottom.
2. ugly. I plan to coat this in rocks with epoxy. Once covered with coralline, it should be hard to see. The aquascaping will hide it pretty well also. This will be plumbed like a peninsula tank, with all the ugly stuff on the left side.
3. clogging and critter intrusion. I am wondering what size holes to cut to prevent the thing from clogging - and how long I can expect it to last.
4. Hole spacing and other details... comments?

 

[mcarroll]

Intriguing! Why this vs another solution? (knowing helps understand The Mission)

 

[BestMomEver]

On our 500, we built a PVC rack to hold the 450# rock we had. Before we installed the rack, we made it part of a closed loop and drilled 100s of tiny holes in it. We had constant movement from under and between every rock. SPS growth was crazy and the tank stayed pretty clean. We had a sand bed and the bottom pipe sunk down into a little. Never had a problem.

 

[lion king]

You do want activity at the surface to help with O2 exchange, that may be why the bottom thing fell out of favor. You can even see a film on the surface of some tanks without adequate surface agitation. And yeah it may not prove to be that attractive.

 

[cracker]

Would this be the main return pump ? If so, even a whole lot of hole this would greatly restrict the pump & slow the turnover rate big time. Maybe?
I like the idea if it was a separate pump. I think a 10 ft tank will need all the turnover& flow you can get !

 

[Salt1972]

Our returns go through a zig zag 'spray bar' under substrate. It's almost like an old under gravel filter in reverse. Our substrate remains very clean with minimal vacuuming. I'm not sure about the impacts to the nitrogen cycle, etc. but this tank is night and day easier to maintain target level nitrate & phosphate compared to other systems we've run. To answer the need for surface agitation, we have a dual overflow and 2 Jebao PP8's in our 125g system.

 

[FishTruck]

Thanks guys!!

When my tanks get old... the sandbed eventually gets nasty. The goal would be to make sure detritus only accummulates where I can see it. I stir my sand bed, so I would push it away from the glass, scrape off the coralline, and the flow would tumble the substrate it back to the glass. Or... if its barebottom - Id just agitate the detritus.

Yes, this is just a strategic placement of the main pump return. I currently use eductors, but getting flow at the bottom is always a challenge. I plan to use a basement sump with a pressure rated pump and the total cross sectional area of the holes will probably be greater that the diameter of the return pipe - so there should be plenty of sump turnover.

I think building it into the rock support would be even better... but I want this separate from the pvc supported rock structures, so I can fiddle with my aquascape.
Ill ponder that.

The main flow of the tank will be from maxspect gyres pushing flow across the top - all together to create the most efficient gyre type flow. On the reverse action, they’ll sweep the whole surface right into the overflow.

 

[mfinn]

I currently have a tank with a bottom spray bar.
I made 1" long slits instead of holes to help keep them from clogging.
I had a previous tank that I used 1/4" holes and after 4-5 years the amount of sponge growth ( and other unknown growth) inside the pvc pipe really clogged it.

I use a siphon break and a wye check valve, but once about 4 years ago, they both failed. Fortunately I was home at the time and was able to prevent the entire tank from emptying out on the floor.

 

[FishTruck]

The rock structures will be five separate masses, sitting on pvc tripods, so the live rock will be floating above the sandbed. They can straddle the pipe. I need to prevent them from getting cemented in by the sandbed - which is what happened in my current 300. I have been trying for 35 years to master aquascaping, and still struggle. So... I want to be able to pull out my mistakes easily.

 

[FishTruck]

I currently have a tank with a bottom spray bar.
I made 1" long slits instead of holes to help keep them from clogging.
I had a previous tank that I used 1/4" holes and after 4-5 years the amount of sponge growth ( and other unknown growth) inside the pvc pipe really clogged it.

I use a siphon break and a wye check valve, but once about 4 years ago, they both failed. Fortunately I was home at the time and was able to prevent the entire tank from emptying out on the floor.

Two questions....
Did the slits work?

And... did you come up wirh a better anti siphon plan??? That’s the part that scares me!!! I know check valves fail notoriously... thinking about it....

Two check valves? Three?
Fixed redundant siphon break with snail guards - even better... above the waterline?

 

[mcarroll]

Just my 2¢: I think it's a great way to execute a closed loop, but seems over-complicated for delivering return flow.

As long as you add a siphon break near-but-below the surface, that shouldn't be a worry.

The better plan for detritus is to keep is suspended in the first place with higher-velocity pumps like the Tunze Stream series. Detritus always ends up coral or skimmer food in my system. Last time I had to clean out my sump was years ago....still pretty clean today. I have one bare-bottom tank on the system and one with sand. Heavily coral oriented....always low (or even zero) on fish....was the plan from Day 1.

 

[mfinn]

Two questions....
Did the slits work?

And... did you come up wirh a better anti siphon plan??? That’s the part that scares me!!! I know check valves fail notoriously... thinking about it....

Two check valves? Three?
Fixed redundant siphon break with snail guards - even better... above the waterline?

Slits seem to allow more flow and less clogging over a 4-5 year period. I checked the pipe with slits recently and they seems relatively clear of sponge/detritus as opposed to the one I had with just holes.

The huge weak point in a bottom spray bar is the fact that it can empty the tank in a worst case scenario.
It almost happened to me. I got very, very lucky.
If this had happened during the night when I was asleep, or if I had been gone for a few hours.
Things would have turned out different.

I have a fairly large siphon break. A 1/4" hole. I drilled it at a downward angle to prevent water from wanting to spray up. Algae building up is a big concern. It seems to grow near the hole. Other than making it a part of weekly/daily routine, I'm not sure what else can be done.
The wye check valve does work, but it does have its limitations.

 

[ca1ore]

Would this be the main return pump ? If so, even a whole lot of hole this would greatly restrict the pump & slow the turnover rate big time.

Yes, and why I wouldn't do it. Well, actually, I did do it ..... once. Not a spray 'bar' but an acrylic box that supported the rock structure and had a whole bunch of holes in it - and it was closed loop,rather than the main return. Worked OK, but put enormous back pressure on the pump and the holes invariably got plugged .... usually where I couldn't reach them. Now I just have my main pump return fire directly down behind the main rock pile.

 

[FishTruck]

Hole clogging is the main barrier. I like the slit idea.

here's a great anti siphon solution.

 

[davocean]

I had this in a 180g many years ago when they sounded like a good idea for hitting dead spots behind rock, but inevitably the holes will plug and it's a major pain trying to get to it to maintain or unplug it.

 

[MaddyP]

Sorry for opening an old thread, but how did this work out for you? I am considering a similar idea in a *much* smaller tank...

 

[mfinn]

Sorry for opening an old thread, but how did this work out for you? I am considering a similar idea in a *much* smaller tank...

I still use this bottom spray bar on my small tank.
As mentions, holes eventually will plug so I use long slits.
The huge downside is that you risk emptying your tank on the floor if any of the methods you use to prevent it, fail.

 

[MaddyP]

I still use this bottom spray bar on my small tank.
As mentions, holes eventually will plug so I use long slits.
The huge downside is that you risk emptying your tank on the floor if any of the methods you use to prevent it, fail.

Glad to hear! I think this would fit perfectly for my Mr Aqua 12G build.