Backyard Aquaponics
A place to discuss aquaponics

Hello all. This is my first post - I'm a bit stuck and hoping you guys can help me out.

I've got a small clay media bed system in my garage at home with a few goldfish which has just started to produce plants - so far all good.

I've now got the opportunity to set up a demo DWC system and am struggling with the basic set up/pump size etc. I've got a few questions - have searched existing topics but can't quite find what I need, sorry in advance if peeps have answered this stuff gazillions of times already...

This is what I've got:

Fish tank vol 783 L
4 grow beds that are 162 cms x 40 cms
Sump - not sure capacity

These are my questions:

How deep should the water in the grow beds be - I've read 20-25cms, is that what works for most people?

How many times should the entire volume of my fish and sump tank water move through my grow beds each hour? How do you determine this?

If it's once per hour, I reckon that I need a pump around 1500L/hr; am I right? (Head height will prob be around 1.5m.)

The pump goes in the sump, water is pumped from sump -> grow beds -> fish tank via gravity ->sump. Is this correct?

In this system, the sump also contains the mechanical filtration. Are there any other main components needed in a small system like this?

Many thanks in advance, any help would be fab. Happy Sunday.

Hello Denise and welcome to the forum. The only bit I can help you with is the grow bed depth and you seem to have that OK. Don't forget that the top few cm of clay media need to be above the maximum water level.

When you say 'a few goldfish' check that you have enough goldfish to feed enough to provide nutrients for the size of beds you are going to set up. I tried to make a few suggestions on a thread called 'new system advice' yesterday. Maybe check that out and see what you think.

Keep checking back here as there are a lot of people on here who can give you good advice (better than me) about DWC. Good luck.

30cm water depth is the most widely recommended for DWC, and the depth most commonly run by the majority of large commercial operations.

Is this a separate new system?... Where is your bio-filtration coming from and how much will there be?... That determines how many fish the system can safely stock and therefore how much nutrient there will be for the plants, as KE suggested.

Thank you! Yes the top few cms of clay media are above the water level in my home system. Having said that , although the water level doesn't reach the top, the clay pebbles never completely dry out, is this going to be a problem?

I'll check the 'new system advice' thread, thanks so much.

Thanks Mr Damage.

My media bed system is in the garage at home and the DWC system is in a different location - totally new and separate.

Good question re the biofiltration. Obvs in the media bed it's the pebbles - I've got 90L of pebbles. And I've started with 4 goldfish. Does that sound OK? My fish tank is 145L.

With the new DWC system I don't know what to do re biofiltration; can you offer any advice? I didn't source the system equipment, but I've been asked to set it up and run it. I'm really up for it but my only experience so far is with media bed and DWC seems a bit more involved.....