Backyard Aquaponics
A place to discuss aquaponics

The tomato plant I put in my AP is not doing well. It has been in there for about a week now but it hasn't grown at all, it just turned purple. The other plant that I planted in compost is doing great and is getting nice and big. (comparison pictures are on my website)

I first thought my system hasn't fully cycled yet. I figured it wouldn't need much cycling since I put a good load of sand from my well established fish tank in there.

But I don't have ammonia issues, so I guess the bacteria are doing good. I just did a water test:
ammonia: 0
nitrates: 12.5 mg/l
pH: 9
tds: 1650 ppm :shock

The goldfish should have a pH of just over 7 and I remember the TDS reading should be about 200 - 400 inaquaponics, with 2000 ppm (which I'm getting close to) is deadly to fish. Something is not right here. I think my grow bed medium might be leaching something into the water.

Purple, Hum, sometimes that can be a sign of potassium deficiency depending on how it presents.

Sounds like it may be a pretty new system, am I right?

Have you tested for Nitrites? Have you salted at all (that will throw off TDS readings but if you salt much it would probably put the TDS reading off the range of the meter.)

What is your grow bed media? I would ask how the fish are reacting but in my experience, goldfish may not bat an eye at something that could kill lots of other fish.

Nitrates can go pretty high before killing fish (the bigger danger with Nitrates is long term damage.) Of course if salt and/or Nitrate was really high when you transplanted that tomato plant, it is possible that there was some "fertilizer burn" to the tender damaged roots upon transplant. This is usually a more common problem when people transplant into a hydroponic system with full strength nutrients. Transplants and seedlings generally like weaker nutrients till they recover from shock. This usually isn't an issue in Aquaponics though.

I have same with collies, is their anything that can be added to boost things up, my system is just re cycling after pump and filter changes

This gets bandied about a fair bit:


As you can see, at PH 9.0 your plants are having trouble taking up a myriad of nutrients. I'd say get that pH down. People will say it will naturally drift down, but at 9.0.... you should probably try to bring it down slowly via other means. Plus if you don't actually HAVE any of those trace elements then you have problems too. People have recommended I use seasol to boost the trace elements.

Well, I couldn't find anything that looked like your tomato. I checked the two sites I know about for tomato deficiency:

http://www.hbci.com/~wenonah/min-def/tomatoes.htm
http://www.ext.colostate.edu/PUBS/Garden/02949.html

But neither really describe or have pictures like yours.... it's REALLY purple...

Interestingly, this ladies seems to indicate that temps turn a tomato cold.

And finally, this site says it's both, and links to yet another site which you can see what a phosphorous deficiency looks like. Looks like what you've got since the other one is outside as well.....

What medium were you using nico? It must be that whats causing it

There's something in this link regarding purple tomarto's ( yes the r is there for pronunciation pourposes) ,,

http://www.buzzle.com/articles/tomato-p ... eases.html

If in doubt spray with Moringa juice extract.

pH 9 .... just what are you using for growbed media Nico???? Draino granules

Seriously... your water is caustic enough to peel the skin off most fish....

And as Gemmel says (see the chart) will prevent almost all nutrient/trace element uptake....

Which leads me to another question.... just what is it thats in the water to give the TDS reading you're getting....

More info on your design please Nico.

I just bought a new pH test, just to be sure, but it's also showing a pH of 9.0

Since the plant was turning purple I went looking for causes. I found information on shortage of phosphorous as a possible cause. Other information I found was about adding wood ash to the soil of a tomato plant and how this method of adding trace elements was very effective and almost impossible to overdose. Well, I added some wood ash to my AP (and to the tomato in compost) you think this has messed things up? I have to admit that I haven't done a pH test on the system before, so I have no pH data from before my little trace elements addition.

The media I'm using is 'split gravel' at least that's what the sign in the shop said. I'm not sure exactly what kind of rock it is. It's grey-ish when dried up, but black when wet. It also contains a fair amount of white and translucent pieces.

I have not tested for nitrites, I don't even have a test for it. From my experience with aquariums I've learned that nitrites readings aren't that important. If ammonia is undetectable and nitrates are on the rise, that must mean that nitrites are being converted and shouldn't be a problem, right?

I scooped some gravel out of the grow bed and washed it with tap water. I'll let the washed gravel sit in a jar with clean water (pH 7.0) over night and see what the reading is tomorrow.

The clean tap water, has it had a chance to outgas CO2? I learned something a while back. I couldn't figure out why my pH kept climbing in my Hydroponic system cause when I tested my water's pH it said 7? Well I tested that pH right after pulling the water from the tap (or well) cause I didn't know about how CO2 and O2 affect the pH of water. Anyway, water right out of the well is usually low on O2 but high on CO2 which will cause the pH to seem low right when you draw it but after it has had time to outgas or aerate, the pH will come up. So now I know to air my water first before checking the pH and I found that my tap water is really about 8.

As to using those ashes, well, they are probably what brought your pH so high. I don't know who told you that you couldn't overdose on ashes because that is probably quite misleading. Ashes or Potash will both cause your pH to go up big time. The caustic part of making soap comes to mind, if you don't have lye on hand you can soak wood ashes to make old fashion soap.

Just for a little science experiment, you could soak some wood ashes in water and then test the pH. Do be careful though as if you spill the solution on yourself or get it in your eyes, you could really hurt yourself.

Anyway, I advise some water changes and perhaps rinsing through the grow beds with some clean water (run that to waste rather than washing it into the fish tank.) You might want to do this a little at a time since sudden pH changes are sometimes worse than the wrong pH.

Benefit to wood ashes is they are a good source of potassium provided you can keep from bouncing your pH.

Which aint going to help ANYWAY because it looks more look like a phosphorous problem.

I hope your tomato recovers, but it looks like it's in a really bad shape.. I've had a few tomato plants turn that purple too, in my dirt garden - I thought it had something to do with the soil being low in nutrients.

My AP tomato is turning purple too, but it's only the oldest leaves and it's still growing and flowering. I thought it was a phosphorus deficiency too, but yours is clearly in a much worse shape than mine.
My nutrient levels are very low though (few fish) and so is my pH - pH is at 6 and if it wasn't for the shell grit it would've dropped even lower.



I think getting the pH to neutral like Gemmell said would help in the nutrient uptake.

I just tested the water that I put in a jar with some of my grow bed medium. The pH is at 9 again. I didn't let it outgas CO2, so I'm trying again. This time I put some water from my rainwater barrel in the jar, which has a pH reading of 7.5. It also contains some water fleas, we'll see if they survive.

The pH of my test jar has gone up to 8.5, I'm sure it will be 9 by tomorrow morning. The water fleas still seem to be doing fine though.

So, it looks like I need to get some new gravel, which means back to washing gravel again I'll be sure to get a hand full first to test its effect on the water...