Welcome & happy Thanksgiving. Post this in the Hydroponics Forum where the commentors are used to the artificial conditions and qualified with their experience to comment.

The plant is starving for light IMO, yet at the same time you are burning it out. Plants need to "sleep". Intensify the light to 16 hours daily and give the plant a rest. Seedlings can tolerate continuous low light, but fruiting plants will be hurt.

The pot is not limiting at this time but it should be repotted as it will reach it's limit gradually eventually. You already have some salt build up. Cut back on the fertilizer in general. You were right about cutting out the excess nitrogen. Problem is you have another astromomically priced mystery product which doesn't seem to advertise their NPK+micro composition although it may be on the label. In the hydro forum someone may have experience with this formula although at this time of year not many are usually paying attention to the posts. EC max, 1.5 mS/cm. I know they ask for more, but that is to make you buy more product and burn out your plant under the mild conditions indoors.

PC

Here is a link that might be useful: GW Hydroponics forum

Hi PC, Happy Thanksgiving and thanks for the reply!

I'll bring the lighting down to 16hrs. Initially the grow light was a few inches above the plant, though with the new tent I had raised it a few feet above to get the light spread covering the floor where the herbs and lettuce live. This has made the plant stretch right out trying to get to the light. I'll raise the tomato plant within a few inches of the light again.

Analysis of the Ionic is N-2.3, P-.33, K-2.9, Ca-0.95, Mg-0.42 (%w/v)

It also contains all the trace elements. Recommended EC is approx 1.4-1.6mS/cm which is a little above your recommended max. so I'll drop the concentration a bit. I thought an excess of calcium could be inhibiting nutrient uptake so I've stopped the nutrient the last 4 days, just water but have seen little difference.

I plan on mixing my own nutrient soon, I'll be testing it on a batch of lettuces to see how the ratios affect the yield. Though this Ionic is only $8.00 and at the listed dilution will make over 1000L of nutrient.

How do you know I have excess salt? Is it something you can see with the plant?

Thanks for the help, I'll make the changes as per your recommendations and post how it goes!

Hi BennVenn,

I didn't realize you are in Australia till now... who in their right mind isn't growing their tomatoes outside down under in this wonderful season? You know 80% of the North Americans are foaming at the mouth just waiting for Spring here ;-) Just joking around ... I'm sure this is a great learning experience. Let me just give a few pointers and address a couple more doubts you had.

OK, $8/1000L for an all-in-one product .... hmmmm Unless I'm wrong that's 3 cents a gallon, way to go mate! .... wait, let's just look at it to be sure ...

OK, the formula is no good for fruiting tomatoes, though it ought to be ok for greens and herbs. Potassium nitrate was not the way to adjust it, it should have been adjusted with sulfate of potash, and we don't knowthe micros so who knows except the leaves don't show any problem with them yet. Too young to say really. I looked at the way the leaves curl in your excellent pictures and that is why I thought you had some accumulated salts already. But it could be that the plant is simply weak. Both are likely. Coconut based substrate is less forgiving on roots than a mineral substrate and when repotting that is an art, not a science where you rip as few roots as you can and open it up somewhat, and put it in its new place avoiding compacting in any way so the roots have time to spread out. I think your comments about roots and water are not far off the mark, except that it is oxygen, not water that is getting excluded and this will be a risk of fungal problems now ... another reason not to dawdle on repotting.

We didn't talk about the composition of your source water. 16 CF is fine at this stage including the water ;-).

OK, if that is fine ...back to the formula, if it is one liter (100:1), you are blasting the poor plants with nitrogen, and unless your source water is passing through a calcite mine, the calcium is not a problem, but will likely become your first deficiency ... it's too low. The formula will work fine at 200:1, but as the fruit load increases, then iron must be added as long as you want to use this sub-optimal tomato product.

What kind of grow light do you have? can it deliver roughly 500 W/m2? OK, well, at least 350, but to each of the leaves? All right, you can twist the tomato plant's arms some and have 200, but that will only get by. Unfortunately it is the lower leaves that are doing most of the photosynthesis and the bulb must be near them unless it is one of these expensive new bulbs that claims a mini-solar directed output. Still the nice reflective room you made is better than I ever had.

Your choice of plant variety is a problem to light up. It is a vigorous indeterminate which needs to make lots of plant mass to complement that fruit mass you're after. Consider a manageable dwarf variety for indoors like that ... and adjust your expectation actually, back to being realistic. You can utilize light with enormous efficiency then. Google the Southern Hemisphere dwarf project and get a good one of those and you'll really have a wonderful project.

OK, I hope I helped more than I confused... but I'm thinking it might be a bit much ... let me know if it's helpful or I if need should clear up or said something dumb lol.

PC