Backyard Aquaponics
A place to discuss aquaponics

Hello All,
I'm a newbie to AP and am getting frustrated by a couple of issues. I have slow growth and black edges on my plant leaves which end up getting crispy and dying. Some leaves are fine and almost all plants have new growth (albeit slow) There is algae growing in some small areas getting sunlight, so I think the system is healthy. I have a 55 gallon plastic drum with approx 20 fingerling goldfish which pumps up into four PVC NFT tubes, which drain into two 20 gallon plastic barrel bottom grow beds. (Pictures attached) The system is about 7 weeks old, I started adding iron chelate a couple of weeks ago which seemed to help some of the plants. I have a PH of 7.8-8.4, been feeding the fish flakes 2x a day and they seem fine. They just do not look as good as other systems I see here. Nature has also made a negative contribution with all the locusts/katydids here this spring and pre-summer, tomato, broccoli and pepper plants all show signs of being eaten on. Help please!!

I had exactly the same prob early on. My prob ended up being that the live stock (5 yabbies) were not producing enough nutrients.

Looking at how many plants you have there I suspect that either your 20 tinglering goldfish are not producing enough nutrient, or you are not feeding them enough. Fish flakes are also not going to do the job, you will need a high protein aquaculture or pond food.

Have you tested system levels. If nitrates are at zero this will probably be your problem.

Also your ph is getting to the levels that will cause various nutrient lock out issues I think. Maybe apply floriar spray of seasol. It will ensure the nutrient go right to he plant and don't get lock up in chemical reactions in the water.

The algea will probably be stealing the small amount of available nutrient left!

All in all I'd say you are suffering from various sources if nutrient deficiency that are combining to cause the bigger prob.

Edit- I hate typing on my phone, auto correct always sticks in the wrong two letter words

Thanks for the responses. I am almost out of goldfish flakes and have purchased pond koi/goldfish pellets, hopefully that will help. I also plan to purchase some seasol to spray on the plants. I only have a PH test kit right now, need to get a nitrate kit as well. Well test tonight and report tomorrow. Thanks!

Feed more, and give it time. My system is 6 months old and is really taking off. The first few months saw little to no growth. Now everything is so thick I can't see the river rocks.

Looks like classic symptoms of potassium deficiency.. Seaweed extract will help, but unless you want to be dosing the system all the time you really need to get a good quality aquaculture feed. That doesn't mean expensive colourful koi pellets, they are usually a rip off and won't help your plants.. The feed we use, smells like fish, and has quite a high oil content and we hardly ever have to add any supplementals to the systems.

Does everyone add nutrients, I have never added anything other than fish food.

I think it really depends on your feed... Perhaps once a year or so we may add something here if we think there's a slight deficiency showing.. Some systems have possibly never been dosed.

As EB has said, it does look like it’s probably Potassium deficiency, with the yellowing and necrosis of the margins… and it’s especially likely seeing as you have a lot of Potassium hungry fruiting plants in the system, tomatoes, peppers etc, and are not using good quality feed… but I have to ask, have you added any salt to the system?

Update: Bought a test kit for Nitrites and Nitrates, both were at or near zero. (Thanks DrLuke). Went to two of the larger Nursery's as well as HD and Lowe's, NO SEASOL, Bummer! They all had similar products, one was simply called Liquid Seaweed and the other was Liquid Seaweed and Fish. The latter product had Nitrates listed as a content, is this the one I should buy?

Mr Damage, I have not added any salt to the system, I have some sea salt that you would use in a salt water aquarium, would that work? if so, how much do I add?

Earthbound, what is the name of your fish food or a similar quality product? Thanks!

Again, Thanks to all for your comments!

Liquid seaweed is what to look for in the states. I use it and it is great.

No don't add any salt. Salt is only required for the fish if you have a Nitrite spike, or they have other health issues. I only asked as excess sodium (salt) in the system will show as yellowing of the leaves and burning, or necrosis of the leaf margins... but if you haven't added any salt then I would say your problem is Potassium deficiency as EB suggested.

You could try foliar spraying with Potassium bicarbonate, sold here in Oz under one brand name as "Eco-Fungicide"... try not to let it get into your GB's or system as it will raise the pH and yours is already high. It's used by AP'ers with low pH to not only raise their pH, but add Potassium at the same time... two birds!

You could also try burying banana skins, or even whole over-ripe bananas that would otherwise get binned, into the gravel GB's.

Burrying bananna skins worked for me but it was a slow process. My concern is that your nitrates returned a zero result, maybe potassium is not your only deficiency but is the one that is showing. Check you did the test right.

As for dosing with nutrients helo. As eb said, it's not necessary if you have good feed, but i now add a cap fully of seasol to my system once a month+seasol spray+a tiny bit of iron. I might not need them, but there is nothing wrong with giving your plants a little tonic to keep them healthy and growing fast. This will help fight of bugs and disease. I'd rather have a safety net than try to recover from a problem with sick plants. As I get more experienced I'll probably start dozing every few months instead.

My goal with aquaponics is to not buy any chemicals/additives to put into the system, just fish food. I am going to do everything I can to stick to that.

So far so good

You definitely have the stocking capacity to do that though, many others don't. Even with 25 trout I got iron deficiencies about a two months back. That's why I've started including the iron in my monthly dosing.