Backyard Aquaponics
A place to discuss aquaponics

Hello,

We've been running an AP system in our basement since April. Our Basil and lettuce grows fine for a few days then get gray/black spots on the leaves which eventually kills the leaves and stops growth.

The AP system has a 75gal tub for Tilapia and a 2"x12"x6' grow bed. A large grow light is on for at least 14hrs a day. I had a siphon set up but it was filling within 5min and draining within 3min, so I switched to ebb & flow. It now fills for 30min and drains for an hour (timer has 30min intervals). I add a bit of Maxicrop every 2 weeks.

The fish are fine, but my plants just seem to stop growing at a certain point and get this gray/black stuff on them. Any suggestions?

Thank you for your help!

How high is your water level?

About an inch below the top of the media.

I thought it was due to the humidity. So for the past two weeks I've been running a fan and leaving a window open during the day to generate air circulation, which greatly reduced the humidity, but did not improve my plant issue.

Having the same issues here as well. We have ours in the basement and it has been running since July 2013. Is this just because it is a new system? Our leaves look the same as yours do.

Can't tell much from the pic but it sounds like a mold problem. The gray would likely be the spores and the hyphae would be growing inside the leaves. You might be able to look at the gray area with a magnifier to see if you see mold spores. Are you planting the seeds in the bed or transplanting from elsewhere?

Two weeks ago I took a close look and found very tiny, thin yellow bugs on the leaves. They were on the plants that had the issue. I did some research and made a garlic/onion/cayenne water mix and sprayed the leaves. After a few sprays and manually removing some of the bugs the problem seemed to go away. A few times the bugs came back but were easily eliminated and the plants have made a tremendous improvement. I have no idea what the bugs were but they seemed to be eating or sucking nutrients out of the leaves....

I had transplanted seedlings but now am just planting seeds directly in the bed.

The bugs you describe sound like thrips.

Or possibly mites.

Dropped in on a friend of mine the other day and some of his plants are struggling.

One more

With the exception of the lettuce the cooler crops look better. What are his air and water temps like Stuart?

That is funny.

When the photo was taken was just after the cool change started coming through yesterday. FT temp was 25c air temp was hot.

The greenhouse is only about 2.4m tall, 8 m (long) x 4m (wide).

I'm not sure what's going on then. I noticed the media was pretty small but while it might clog easier I don't think it's the problem. Maybe there's just not enough nutrients to go around and the Chard is sucking most of them up. It looks like a Nitrogen deficiency because of the even yellow on the lower leaves (the veins don't look darker green).

Cheers

The top 2 to 3" is the small bluestone gravel but underneath that is 20mm scoria.

Nitrogen deficiency would make sense because he doesn't have very many fish.