Backyard Aquaponics
A place to discuss aquaponics

Hello,

I'm new to this site and AP planning about to build my first system in a greenhouse want to have a small raft some grow beds/buckets and maybe a few towers. I know it's allot but I'm a disabled vet and I'm home all the time so I should be able to keep a pretty good eye on it. If all goes well I want to go commercial eventually. One question I have is how much grow space can I put on a 1 tank it will be a stick tank 4x2 round?

Thanks

I seem to remember reading somewhere that you should have twice the grow-bed gallonage than you have in the volume of your fish tank, although I've never even come close to that amount of space.

Whether you have a flood/drain or constant flow setup also probably matters, because you (obviously) certainly don't want to pump your fish tank dry trying to fill up an overly-large flood/drain bed, and while you might have more leeway with a constant flow system you'll till have the possible problem of your fish tank overflowing if you're ever hit with a power outage.

I wish I could give you some sounder, more forumlatic answers, and perhaps some of the other posters can, but I think we'd need to know some more about the variables in your system.

Keep at it though!

Variables such as? And I'm sure somebody on here could most of the stuff I've read makes me think that this is a pretty well informed group.

The more fish you have, the more wet media (acting as a filter and nitrification area) you need. Or if you turn the calculation around, the amount of wet media you have tells you the maximum amount of fish you can have.

From this thread:
viewtopic.php?f=12&t=6646
which has a lot of really interesting discussions (it's definitely worth reading in full) the generally accepted maximum stocking density is 3 kilos of fish = 100 liters of wet media = 50-100 liters of water in your fish tank. (1 lb of fish = 5 gallons of wet media = 2.5-5 gallons of water in your fish tank.)

This is the maximum stocking density, so it's also suggested that you start with about half the weight of fish your system could theoretically handle, so you've got more leeway while you're learning. Also, bear in mind that your fish will grow, so you need to work out about how much your fish will weigh when they're adults (or the plate size you plan to harvest at) and get that number of fingerlings, not that weight in fingerlings.

Time to pull some numbers out of thin air for an example...

My big system that I'm just starting to build is going to have a bit over 2,500 liters of water in the fish tank. (It's going to have about half that amount in the sump as well, but we're not counting that for this calculation - it's fish swimming room that matters, not total water volume.) If I had unlimited growbed area that would let me have 75-150 kilos of fish (woo!), but I don't (darn).

Working out the planned volume of my growbeds, not counting the top 5cm of media because we're talking about wet media here, I should have... (vague math, handwave, handwave) ...about 1,300 liters. (Sweet! I hadn't done the math before.) That gives me a maximum stocking density of 39 kilos of fish. Because I haven't been doing aquaponics for long and want the wiggle room, call it about 20 kilos instead.

I want to stock silver perch. They're considered 'plate size' at around 500g. I should get around 40 fingerlings to start with; once my system's been running for a while and I feel confident in my ability to monitor things and avoid at least some of the potential HSMs, I can get some more.

Clear as mud?

Uhhhhh.... yep about as clear as gumbo mud.

And thank you for the thorough response.

Forgive my ignorance HSM?

"Holy Shit Moment" Things like "Holy shit, something leaked and all my water is on the floor instead of in the tank", or "Holy shit, how did my water quality get this bad this fast?"

How many growbeds etc you can have will be determined by a bunch of different things. For raft beds (aka DWC, deep water culture) NFT (nutrient film technique) and towers, the limit isn't determined by how big your fish tank is; it's mostly how much nutrients are in your water, i.e. how much are your fish pooping and are you adding supplements. That's because none of these techniques cause fluctuations in water level elsewhere in your system.

Depending on how you run them, media beds might have a hard limit based on the size of your tank, or they might not. If you have a sump tank, or run them on constant flood, they won't cause fluctuations in your fish tank's water level and the only limits are how much space you have, how much nutrients are in your water, and how many growbeds you want to be looking after. ...Oh, and how much money you want to spend on setup, and/or how good you are at finding cheap recycled things to use.

If you don't have a sump, and run your growbeds on some form of flood-and-drain, the water level in your fish tank will go up and down as the growbeds drain and fill. If you have a big growbed, or if multiple smaller growbeds get into sync and all fill or drain at the same time, you can either pump your fish tank dry or overflow it if you didn't plan properly. There are ways to avoid that happening, but again, you gotta plan for it. If you do have a sump but it's too small, you can pump the sump dry and kill your pump, or overflow that.

So... are you going to have a sump tank? You say you're going to have a stick tank... what's that mean? And 4x2, is that in feet?

ETA: did you mean stock tank?

Yes stock tank. And yes I'm talking in ft. Sorry me and metric don't convert well.

And yes I will have a sump tank I was planning on my DWC doubling as that because I've been told I can make that work.

Just for clarity here's the basic run down of my system.

FT to bio filter from there to header system in top of green house. Flow down into buckets beds and towers, towers will flow into beds then siphon into drain line buckets will drain straight into drain line which will flow into my DWC/sump. From there through a pump with a sand filter back into FT. I know I'll need at least the 2 pumps I mentioned but will I need 3 with that bio filter?

You're getting a bit beyond my capability to give advice there, hopefully someone with more know-how about complicated systems will chime in... but I think you could run that with just one pump if you re-ordered things a little.

You could have your pump in the DWC/sump and split the flow so that half goes to the FT and then gravity feeds through an SLO -> filter -> back to DWC/sump, and the other half goes up to the header -> buckets / beds / towers -> DWC/sump. As long as you're turning the FT volume over roughly once an hour and putting a decent flow through the beds at the same time, it'd work.

The thing that gets me the most is the biofilters. Do they work off of a similar principle as a siphon? Because I don't understand how the water is moving through it without having a pump to pull it out of the filter unless it's sealed airtight. Are they sealed to make this happen?

Nope - most of the filter designs I've seen just have the water moving through under gravity. If it's flowing in on one side, and there's a way through to a lower level on the other side, water will find the way!

What sort of biofilter are you planning to use?

I was going to make one out of the blue 55 gallon drums. But what if the FT and DWC/Sump are on the same level as the Biofilter?

There needs to be at least a little bit of a drop. Doesn't have to be much, just has to be something. I'm planning to make a radial flow filter (RFF) and mineralisation tank out of barrels (mine are black), and since I want the water flow through the RFF to be gentle, having it as close to the water level in my FT as possible will be the way to go. Can you raise the FT a little, or lower the DWC/Sump? A lot of people dig their sumps into the ground, partly to take advantage of earth insulation but also to allow good gravity flow.

Are you planning an RFF, or a swirl filter, or a media filter of some sort, or...? There are a lot of options!

I honestly don't know what half of what you told me was. I am familiar with the media base filter and another with a baffle in the middle where the water flows down one side and up the other through a filter material of some sort.

What if I put the FT and sump which will be 2 foot and 1 foot deep respectively both sitting on the ground and put the bio filter on a stand about 2 ft tall would that work?

I'm going to research the RFF more is there s thread on bio filets on here that you're aware of?

I'm trying to add a photo I drew up how do I do this?

For adding photos, the first and third stickied threads in this section of the forum are useful:

viewforum.php?f=4

This thread shows the style of filter (RFF) I'm planning to build:
viewtopic.php?f=8&t=16970

Here's a video by RobBob showing the one he built. (RobBob's YouTube channel is an awesome resource, he explains how he built a lot of stuff and links to other useful stuff. He's on this forum and generally an awesome dude.)

https://www.youtube.com/watch?v=mKWXkf9j5Qc

And these are his clips that include his moving bed biofilter:

https://www.youtube.com/watch?v=AwW4sKL3ukw
https://www.youtube.com/watch?v=0E2zIGGMdKU

This is Bigelow Brook Farm's swirl filter (another Rob with an excellent YouTube channel, also on this forum, invented GrowGrips which you really should look into since you're planning to do raft beds!)

https://www.youtube.com/watch?v=3yMqbWUoZ1k

And mineralisation tank:

https://www.youtube.com/watch?v=rEDoPr-ZJUI
https://www.youtube.com/watch?v=yS6jp4H03SU

Some people use filters stuffed with shadecloth, netting, dish scrubber pads, bottlecaps, you name it, if it's safe to use and cheap to get somebody's used it! This post talks about some of the options and mentions that some of them are a lot easier to clean than others:

viewtopic.php?f=8&t=26428#p526504

-----

About your filter and sump question... if you're going FT -> filter -> sump via gravity, the water level in your filter needs to be in between the water level in your fish tank and the water level in your sump, so you almost certainly won't need to put it on a stand. If you're going with a media filter, it's generally a good idea to put two filters in a row, the first one being a RFF or swirl filter to take the big 'chunks' out, then the media filter to take the fine particles out, as otherwise your media filter will clog up really quickly and need to be cleaned more often than it would otherwise.