Backyard Aquaponics
A place to discuss aquaponics

Hello all! I am new to aquaponics (although not fishkeeping), but I did my research and hooked up a DIY aquaponic system to my 32 gallon goldfish tank. The growbed is a 10 gallon tank I got in a sale (20"X10"X12"). I used a DIY PVC overflow to drain the water to the growbed since it is lower than my fish tank and I can't drill it. The water is sent back via a pump on the other side of the growbed. This is a continuous flood system with the water level about 4 inches below the surface. I planted some cherry tomato seeds in there and about 6 of them sprouted in a week. I realize that a 10 gallon tank is not going hold 6 tomatoes since they would probably get fairly large. Do anyone know how many tomato plants I could have space wise in my growbed? I have 2 fancy goldfish who are both heavy poopers in the tank. I also have tons of invert and ottos to control algae. Also, how far apart should the tomato plants be?
Help is appreciated!

Welcome to the forum LWormy

hmm, there really isn't enough information to answer your question. Are you trying to grow Determinate or Indeterminate tomatoes, full size plants or dwarf, under lights or outside. The type of food your feeding makes a difference as well as the size of the goldfish. I think you should start with one tomato plant or maybe two but plan on culling the second one if the first one does OK. There might not be enough nutrients for two tomato plants and unless you can spread them out when full grown you might not have enough light.

Yep, you'd just want one tomato plant there..

This was one or perhaps two tomato plants in one of my systems a few years back.

Please see pic below for ideal spacing of tomato plants in aquaponics.

I've experimented with tomato spacing a few times, and I've found you need to follow the normal dirty spacing. Last year, I had then too close together, and the yield is crap.

Something like lettuce, you can put them as close as you want, but tomatoes want space.

Well, my tomato is Lycopersicon lycopersicum. It is the indeterminate type and it is grown indoor with a window right above it so it gets about 8 hours of medium intensity light everyday. My goldfish are both 3" long without the tail (5" plus tail) and I feed them 2 times a day with algae wafer or New Life Spectrum goldfish pellet. On average they produce 20 ppm of nitrate a week (I grow mint with this system too and lots of aquatic plants) and my pH is 8.2. Would it be best to just have 1 tomato plant? How big COULD my tomato get? The seedlings are still pretty small (1" tall) so would it be a good idea to cull it yet? I will post some pictures of the system to get you guys a better idea.

Uh, there are no numbers or anything on there. What is the pictures supposed to mean?

WOW! You got that giant plant from ONE tomato? Does it produce a lot of fruit?

Here are the pictures. I grow mint in my Marineland Biowheel HOB filter in my tank and there is a picture of the window I got most of my light from. There is also the picture of my two goldfish.

You may be asking the wrong question......

While spacing is somewhat less of a concern in AP I would be asking how many tomato plants will 2 gold fish support..... I would put bets on only 1 plant. Better to have one plant producing well than a bunch of plants that all suffer. As I found out with my pumpkins this year! Lol

You're gonna have to track your results and provide us with updates now!

That pic means "don't put them in the aquaponics, put them over there in a wicking bed" Tomatoes have a well-deserved reputation for sometimes clogging up huge areas of a media bed with their root ball, blocking water flow and growing into the siphons in their quest to hog allllllll the nutrients. A lot of the time they don't! But when they do, they do it well.

'Indeterminate' means your tomatoes won't stop growing when they hit a particular size - they'll keep going. They're also going to need some sort of support or they'll sprawl all over your floor. If I were you I'd pick one to keep where they are, move the others somewhere else, and start planning what you're going to use as a trellis.

Ok, I think I am just going to stick with one plant then (I don't really want to build a wicking bed because I don't have the space and I don't want to tear my system down again). What do you suggest using as a trellis? Would the plastic tomato support cage they sell at Home Depot work? I have a lot of those from planting tomatoes outdoor but I am not sure if they will leach anything into the water. As for clogging the siphon, I don't think I will have that problem. I don't have a siphon in my growbed and I use a pump to send the water back since the growbed is lower. I will just have to make sure the roots don't get to the pump. The thing is, I have 6 sprouts randomly in the growbed (I broadcasted the seeds) and the healthiest looking ones are all in weird places like the edge of the bed. The only one in the middle is small and kind of weak-looking. Do you think I should leave the stronger one on the edge or the weaker one in the middle? If none of those would work, would it be best to just pull them all up and plant a seedling in the middle?

Will do! I've decided to keep one plant but I am not sure how to pick which one to leave. How do I know which plant to pull up and which one stays there?

I'd leave the one that's furthest away from the pump. If the trellises you have are plastic and haven't been in contact with anything you don't want in the system (like pesticide etc) they'd be fine to use, especially since you don't need to set them up in the growbed - if you can attach a string or something to the window above your setup, you can use that. Does that window open? If it does, you could just tie a knot in the end of a string and close the window on it to hold it in place.

Ok, I will try to pick a seedling and pull out the rest today. They are growing REALLY fast and most already have the second pair of leaves (I am 2 weeks into the system). As for the window, it does not open. What do you mean setting up the trellises outside of the growbed? Can you give me an example of that? I get using a string and all but I don't really know how to do that otherwise because my system is on a countertop.