Backyard Aquaponics
A place to discuss aquaponics

Hi all!

I am in the process of designing my AP system under a Greenhouse. What would you say is the optimal depth for the grow beds?

Chelle

300mm is the "accepted" optimal norm Chelle.....

Thanks! Can get on with more planning.....

It's more like a guide rather than a rule.

300mm is a good 'optimal depth' for a 'multi-purpose' growbed, but it really depends on the plants. For strawberries, 200mm depth would be better. Big plants like fruit trees would probably want 400mm or more.

Makes sense..........

Can you have a mix of sizes on one system? A couple of 400mm and 200mm and then most 300mm? Would it upset the system in some way if I did this?

Thanks,
Chelle

I've got a variety of depths and types of grow beds. I suppose the main reason to keep things consistent is if you are building or buying a huge amount and can therefore get them cheaper by buying in bulk or building all the same design.

If you were trying to balance some specific type of cascade system or something, having consistent size might be important or if it were some automated alternate filling system then sizing might be important to timing to get the beds to all fill the same.

For the average system, variety can be interesting.

I can't see as how it would.
You might have to individually adjust the fill or drain rates depending on how your system is set up.
Just make sure your FT or sump won't run dry, which is no different from if all GB's were the same depth.
Good luck!

I would prefer the different size depths to accomodate some papayas and banana trees in the system but not sure how the water flow would be affected. How is your fill and drain set up TCLynx? Sorry for all the quesions. I am a real newbie at this.

willys_truck - I see you mention individually adjusting fill and drain rates.......If I make sure that the filled water tank equalled all that would be needed by the growbeds in one flush would the shallower grow beds overflow while the deeper ones were still filling without this? Would the inlet pipe have to be adjustable with a valve or something on each growbed? Another thought... distance from the tank would also affect filling rate would it not? ..... cos pressure would reduce over distance. Is this a game of trial and error until all fill and drain perfectly? This is going to be fun! And all I wanted was some fish and salads! LOL

Chelle

The trial and error of overflowing growbeds is all part of the fun. Water everywhere

Let us know what volume of growbed and tanks you are looking at and we can guide you as to pipeing and pump sizes.

The answer could be complex.....

I've tried out all sorts of different methods within my system so it is a bit of a hodge podge. Here is a link to my system thread. Long read but lots of pictures.
http://backyardaquaponics.com/forum/posting.php?mode=reply&f=1&t=3738

For a shorter answer. My pump runs all the time and I have ball valves on the feed into each of the grow beds (well except for the monster bed that is fed by two other beds draining into it.) Most of my beds are drained by some sort of auto siphon or in one case a Flout. I have loop siphons and a couple bell siphons. The monster bed is drained by the use of a sump pump since it is too low to gravity drain by auto siphon.

I also have experience using a flush tank like in a barrel ponics system. I think that is great for a small system but it is not really appropriate for a large system.

What size/scale of system are you thinking of for your first system? Then how big is the next system going to be? There is already another one

Essentially the depth of the gbs is the minimum depth required for nitrifying bacteria to have a somewhat stable environment. The deeper the gb the more stable it is temp wise, the less likely you are to knock out the bio/bacteria.
If ur gb was 10cm deep u may get wide temp fluctuations in it which could knock out the bio. This means the population needs to re establish and has implications for water quality and fish health during the process.
Plants don't need soil, we are really trying to provide a happy environment for the bacteria to do its thing and make our plants grow.
As Rupe says, 30cm is kind of an accepted norm.

Depending on how you are for access around the plumbing, two drain holes and a partitioned deep GB might be an option.
Partition off the media (i.e. have a wall that is sealed on the sides, bottom isn't as important), have a shorter standpipe in the lower section and a separate drain.
Alternatively you could have a mesh that raised one section of a deep GB and have a higher flow rate to that area so it didn't have to wait until the main GB was up the extra 100-200mm.

If can cobble together a picture I'll post it...

The upper picture would need plenty of flow in the shallower section to make sure the plants had water before the level came up above the mesh.
There are disadvantages to both, but since you're beginning, now is the time to consider different stuff (as I'm sure you know).

Thanks. I will. I went looking today for the best stuff to use for growbeds.... whew! I have no access to barrels. Have now decided just to build with bricks that I was given free. The cement will be nothing in comparison to the other pricing. Working hard at getting that GH up...