Sump for a 6'x2'x2'

[ChrisEddy85]

Hi,

I am currently planning to build a 6'x2'x2' heavily planted aquarium and wanted to use a sump for filtration. Does anyone know what size I would need for the sump, as I currently have a 3'x1.5'x1' tank and as I was looking at it last night, it just looked too small...

Furthermore, what sort of pump would I need for the return? As I plan to use and overflow for the intake, it would hopefully mean that in the event of power failure, the sump wouldn't overfill and spill everywhere, but is there any other risks that I have missed?

Finally, anyone know of a good place to get a customised tank and 6x2 metal stand in Perth?

[ILLUSN]

6X2X2 is 650L so ideally you want a pump that can move 3x that volume (around 2000L/H).

you wont need a massive sump if its planted, the plants work as your primary biofilter, most of my planted tanks run on small canisters (2213's or 2217's) with just mech media,

I've got 1 300L plant tank which has 0 NH3,NO3,NO2 and PO4 so i have to add KNO3 daily and PO4 every week just to stop the plants turning autum colours (red orange yellow from N and P defficiencies). All it has for filtration is an eheim 2217, this would have less than 1/4 of the capacity of your 3 foot sump.

[ChrisEddy85]

Could it be an issue if the pump was too powerful? Could it drain the sump dry even if using an overflow.

Through my basic sketches, I have already come up with a solution to this problem. I had an idea that I would have the first overflow that would be plumbed down into the sump before the filter media, and a second overflow slightly higher that would be plumbed directly into the resevoir for the pump.

Therefore, in the result that the flow of the water through the filter media was not fast enough, the second overflow would simply allow for water to still feed into the pump, and therefore prevent a dry-run. This would also help with the heaters, as I plan to place heaters into the sump, in the final resevoir.

[ILLUSN]

not really a problem make sure the water going to the sump is around 40-50mm and it will never run dry, at that sized pipe gravity will easily pull wather through at around 4000L/h, way more than a 2000L/h pump.

just rember to keep your void volume of your sump big enough so in the event of a power failure you dont end up with an empty tank, an overflowing sump and a wet floor :)

[ChrisEddy85]

I was going to have a reasonably high overflow and return point for the tank, so it would prevent the tank from running dry in the event of power failure, correct?

But I see what you mean, there needs to be enough volume in the sump to allow for the maximum amount from the overflow to be in it so that if the pump stops working, it will fill to a point and not overflow.

Another quick question, do bubble baffles work in freshwater set-ups? I don't really see the point, as I thought that water is supposed to be well oxygenated, and that bubbles in the water were a good thing?

[DIY]

Yep you are right - baffles aren't required for freshwater.

For the pump, you also need to take into account flow rates after both head loss and elbow/pipe losses. For example a 2000l/h pump pushing water up 1m head (lift) through hoses and elbows might only flow 700-800 litres per hour

On my 6x2x2 (slightly under) I'm using an Oase 4000ES which is rated at 3900l/h and 3.9m head. I use 25mm hose split into 2 spraybars of 19mm in size and avoided elbows where possible, when I did a timed bucket test I worked out I have close enough to 3000 l/h actual flow.

I did the same test on another tank (4fter) with a 2000 l/h pump max head of 2.4m using 16mm hose including a few elbows the flow worked out at only 600 l/h.... To be fair the pump was a cheapy that I think was over-rated as well.

[ChrisEddy85]

So, a bigger pump then?

The plan is to have the sump directly under the tank, so that the only elbow would be a 90 at the top of the pipe directly before re-entry into the tank. I was also wondering if having a one-way value would slow it too much. I thought this would be a good safety precaution and would prevent and little bits heading back into the sump, as the intake on the overflow would be well protected by fine mesh, but the return would be made up of considerably larger holes, to allow a free-flowing return.

Realistically speaking, this is a long term project and is already going to require a lot of saving, so a few extra dollars on the pump wouldn't make a whole lot of difference.

[DIY]

I thought about a one way valve when I was setting mine up.. it isn't needed to be honest but it probably wouldn't hurt I guess other than slowing the flow somewhat.

The main thing is to have some method of stopping the siphon effect draining the tank into the sump via the pump hose if the power goes out. The simplest and easiest method is to have the spray bars/return very close to the water surface so air is sucked in should the pump stop to break the siphon. A "siphon break" hole somewhere near the water surface or above it will do the same thing.

If it was me I'd go bigger than 2000l/h, you can always reduce the flow if needed but it is very hard to increase it :wink:

You should decide what sort of turnover you would be happy with and work from there. If you want 3x than you need around 1800l/h at approx 1m lift.. so you're probably looking at something like a 3000l/h pump. For 5x you will need something like a 4000-4500l/h pump and for 10x you will need $$$ :lol: :lol:

From my experience I had a 4footer (the one I tested above) running roughly 3.5x turnover and it wasn't enough as I always had particles visibly floating around and not much if anything would lift up and over the wier... I'm running about 5x on my 6footer and it's much better. More would be better still but the discus probably wouldn't like it though

[ChrisEddy85]

Yeah, the current would get too strong for them.

Whats the best type of return fitting? Spray bar?