Backyard Aquaponics
A place to discuss aquaponics

I wonder why one would have a sump in a hydroponics system?
Isn't it easier to just have grow beds above a fish tank and pump directly from the fish tank back into the grow beds?

This question has been asked many times.
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A sump is very important in many of out designs. It's worth looking into.

The hydroponics setups I've seen do have a bucket underneath the trays. The water is pumped up and drains back into it.

As KP says, some AP designs require a sump. CHIFT PIST is one such design. They add water volume, provide a place to grow things like mussels, in CHIFT PIST they absorb the water level changes, and in some circumstances it's "defective by design" to put the growbeds above the tank as they then are too high to tend to!

There's a limit to how much growbed capacity you can have by merely employing gravity drain from growbeds higher than your tank...

i.e ... if you have a 1000L fish tank... and say 3 x 500L growbeds... a total of 1500L of growbed volume....

The media will take up about 40% of the growbed volume => 1500L - 40% = 700L (approx)

If you fill all your growbeds at the same time... you would probably be pumping 5-600L out of your fish tank into the growbeds before they began to drain back....

Leaving only about 400L of water in your fish tank....

Obviously, if you were to increase your growbed capacity... by adding another growbed... you'd begin to lower your fish tank below the dorsal fins of the fish...

That's one of the reasons we use a sump.... Chift Pist ... is another...

For a simple system that isn't not going to be heavily stocked, simply having say a 1:1 ratio of grow beds to fish tank. Simply pumping from the fish tank to the grow beds and having the grow beds drain back to the fish tank is fine.

However, you asked for reasons one would have a sump.
Already pointed out was
Sometimes you don't want a step ladder to reach the grow beds if the fish tank is really tall.........
And if you have more than about a 1:1 ratio of grow beds to fish tank, the water level fluctuation in the fish tank gets a bit too extreme to keep the fish comfortable.

Here is a link to a rather lengthy thread on both ratio and Sump tanks It is right in the top of the Useful info section of the forum and it is sticky.
http://backyardaquaponics.com/forum/viewtopic.php?f=11&t=4622

My personal favorite reason for a sump is.......
CHIFT PIST (and that is with the grow beds filtering all the water before it goes back into the sump and therefore the water going through the pump is relatively clean meaning less cleaning of the pump and pump trap as well as being able to use water directly from that pump to feed NFT or DWC if you wish.)

OK, that helps me.
My system is such that I won't need a sump.
Thanks.

Sump also lets you increase the volume of water without increasing your tank size. This helps a bit in temperature stability and water quality. Also if set up correctly can suck solids from the main tank in to the sump but not up through the GB's.

I added a 250L sump to my 1000L tank even though I didn't technically need to. I chucked a few yabbies in the sump and some water cress to make best use of the space. Having second thoughts about the yabbies though.

I'm not sure why you would want to suck solids into a sump and not into the grow beds. Just means you then have to manually clean the nasty smelling stuff from the sump. I like the solids in the grow beds where they can help nourish my plants. But I do have lots of grow beds and think worms are wonderful creatures.

When I think about it my trout fingerlings are in a 200L drum which sits inside a 5OOOL tank which is about 400mm deep.
I pump from the 5000L tank up through an overhead biofilter.
The biofilter is made of those little orange clay balls which are then baged in open net onion bags.
When the 200L biofilter fills up it then overflows and siphons down to the grow beds which inturn are above the 200L fingerling tank and the 5000L tank.
The grow beds drain into the blue 200L tank and when this fills to a line it siphons water out into the 500OL tank.

I have just one small pump on a timer which is simultaneously accompanied by a very expensive German made silent aerator. The aerator operates to 5 points in the system, one of which is the 200L fingerling tank.

I guess this means I already have a sump. The 5000L tank has in it some hairy back marron, freshwater cobbler, river muscles, a few fingerling trout, 5 koi and some jilgies.
Given that there is no chance (without a leak occuring) of draining the 5000L tank then I certainly have a sump.
However I am about to set up some 400L tanks for the trout and can immediatly see the benefit og fitting these inside the 5000L tank in the same way I have done with the 200L blue drum with the fingerlings.

Interesting Trevor... how about some pics...

Yea i would like to see that also can you give more info on the air pump

Mainly large solids like uneaten food and larger solids. The yabbies in the sump seem to like them. Smaller stuff still seems to get sucked through to the GB's. Anyway solids in the GB's seems to be a point that some people don't agree with.

jpcw - it is for the earth worms to munch on

Who people...??? ...

Some pics of my system: