Weir Construction...

[Aquatopia]

Hi

Im still in the throws of designing my own custome made tank. Its measurements will be 1100L x 700W x 530D (i get width and depth mixed. im assuming width is back to front and depth is top to bottom and length is left to right !!).

I am trying to work out what to do re the weir/s.

I have seen some weir boxes where (some where triangular others were square) the first wall had slots in the top AND the bottom. Im assuming the theory is to draw off water from the bottom of the water column as well as skim from the top. This then filled up against a second wall at a slightly lower height and cascaded over into the main drain chamber (some had a hole in the bottom with or without a standpipe, others towards the top).

I have heard comments that having the slots at the bottom might lead to clogging, and may often be awkward to keep clear.

Other weirs (be they triangular or square) are a single wall that the water flows over and into the drain chamber.

Another is just a box surrounding the outlet pipe towards the top of the aquarium.

SO, I guess Im asking;-

1) One or Two weir boxes for a tank my size ?

2) Which design is best? OR what are the pros and cons of either ?

3) What about extending the weir construction with a sloping channel extending further along the back of the tank to increase the amount of surface skimming? Too ugly compared to potential benefit?

Then the return. I want to do something similar to an article i saw in Marine World where the return(s) was piped under the live rock structure, thus reducing detritus settling as much as possible. (I will hopefully be putting in a closed loop for circulation too).

1) Is it OK to have the return coming in at the bottom of the tank?

2) If i do that should i use a non return valve to prevent possible backsyphoning in case of pump failure?

Sorry this post is so long !

[dan_from_nz]

I have read it is better to have the comb at the top only as the surface water contains the majority of the protines and is the section of the water that needs skimming most

as for the return piping running under the piping you would have to run a non return valve which would slow your water flow

good luck

Daniel

[Aquatopia]

Daniel.

Yeh thanks for that - i thought a non return valve would slow the flow. Are there any figures on how much effect they actually have in terms of percentage flow lost?

[Pies]

I'll take a punt at answering a few questions:

1) One or Two weir boxes for a tank my size ?

Its only a small tank, 1 overflow will be ample. My tank (1500 litres) has 1, and its driven by an IWAKI 100. 40mm hole. I would say, use one, use a 32mm hole (40mm standpipe), and you will have more capacity than you could ever use.

Overflow boxes vs. weir. Seems to be some confusion about what these 2 things mean. Again symantecs I know, so I will explain this as my own difference. Overflow box is the box in the tank normally housing a standpipe, overflow requires the tank to be drilled. Weir, a syphon driven device used to get water out of the tank 'safley' without the necessity to drill.

With that out of the way, personnaly weirs are dangerous (syphon could break, floods ensue).

So we are now onto overflows. I would check richard dursos site, and read all about DURSO standpipes and overflows. Combs ONLY at the top, if at the bottom the tank could drain, water level at the top of the tank could flucuate, getting water pressure right for even flow would be difficult.

Hope that helps. Have a read through my thread, there are some pics etc of my overflow and Durso, and I honestly belive there is no better way to do it. I think you will find that this is also the concencious, with approx 90% of all people with sumps using this system. It works.

If you get stuck or are confused about anything, drop me a line, glad to help. Have build 5 of these now, all have worked out perfectly. Even know where to get the boxes made cheap

Running water returning from sump under rock? I would say its a poor idea. Could drain the tank, take away a lot of pump pressure because of excessive distace, would look bad (you would see the pipe returned into the tank. Bad idea. Closed loop doing the same thing however would be a great idea! You can either stealth the return at the top, or I would reccomend using a Sea Swirl device, these things are excellent.

Pie

[Aquatopia]

PIES

Thanks for all that - phew !

I see what you mean.

When you say sea swirl - these are the electronic boxes that vary retun flow direction?? How do they compare to oceans motions revolutions?

On the closed loop? Could i have one pipe providing "reef-flushing" within the live rock and other returns providing main water column flow?

Will get to grips with your thread at bedtime.

[chimera]

yeah, what pies said but the main thing is keep it simple. less complication means less things to go wrong

sea-swirl rotating return device - exactly that, rotates side to side, used for return.

oceans motions separate (although you could push your return through one) however i'd keep the oceans motion on a closed loop separate.

[Aquatopia]

Thanks chim - thats exactly what i wanna do. I want it all to look good and be efficient whilst providing the best i can within a reasonable but limited budget. (Dont we all). I guess what Im trying to do is the same as you guys but on a way smaller scale. Ive chosen 1100x700x530 because i didnt want too deep a tank for lighting reasons, but i wanted a bit of depth of field - Im hoping to create a similar effect to Steve Weasts tank - creat a channel which draws your eye away from the sides of the tank.

[Pies]

Question - Why 1100? Why not 1250? 1100 means you will be using 3 foot tubes with dead space each end. 1250 is just over 4 feet, so you will have room for the 4 foot tubes and they will be snug but not tight.

Using the Oceans Motions on a retun pipe would be for kamakazi pilots only.

Just go 'up and over' for the return pipe. Looks fine and you can add a sea swirl or whatever else you may think is cool later on when budget allows. I would add that I would not be without the Sea Swirls, for me they are a must have.

Pie

[Aquatopia]

Cheers piezola !

Will re-visit the swirls / revolutions options. Just the one on my tank? Hadnt thought about the tube sizes. 1250 is getting a bit big and it reduces the depth of field effect of having 700 in that measurement. But i see what you are saying about the tubes.

[chimera]

still sounds like a reasonable size, still 400 odd litres. 1200 would fit a couple of halides rather than the need for three whilst still giving good lighting coverage (depending on number of acro's, general rule is 1 halide per 2 foot), 700 deep means you can have a good amount of substrate at the front giving it depth or at least the impression of it!

perhaps a couple of OM squirts would be better/cheaper then? two closed loops independant of each other, running a OM squirt on each. couple of iwaki 30RXT's would be ideal for the closed loop. or maybe even a single OM squirt would be sufficient? check the OM forums. another iwaki for return suited to the your head height from your sump.

[Aquatopia]

Chim, cheers - will think on that one. Are the OM forums on the OM website?

[chimera]

yup, http://www.oceansmotions.com/forum/

[DiverJohn]

Giddy,

OK FW dude sticking his head into the SW section, so dont be mean :lol: :lol:

POM, Pies is right about the tank size... Go just over 4 foot if that the approximate size you want. My FW tank is 1150 long, it is the most frustrating size! The difference in volume between 1150 and 1250 is "in the scheme of things" so small it is insignificant . But when it comes to lights...different storey.

I am trying to grow plants (and doing a not bad job of it i think ) but would dearly love the extra "foot" of lighting I could get using 4foot tubes. Not to mention the TWO dark spots at either end. With 5 tubes on my tank I am getting 150W, of course I could alway add a 6th tube but still... the 4footers are always going to produce 20% more light (on paper 3foot =30W 4foot=36W) Add to that the 4 footers are probably more common, you get better selection of tubes/colour. Finally a 3' is about the same price as a 4' !

My 2c

John