Backyard Aquaponics
A place to discuss aquaponics

Hi All,

Looking for help as this is getting a bit desperate.

Water is at 27C / 1300 ppm / pH 7 (around normal for me) ppm has been a little higher than usual recently)

Plants wilt and die. I have some older rucola in there and when one of them wilts the center of the stem is rotten and yellow, but now it's spreading (i think) to otherwise healthy plants in my DWC beds. Plants in NFT tubes seem ok. Basil goes from being harvested and healthy a week ago to nearly dead in less than a week.

Does anyone know how to stop this or am i going to have to do a big kill off and quarantine?

Please help!

Looking at the roots, I would suggest you have some sort of root rot disease, ie Pythium etc. The roots should be white. or a slightly off-white.

Water temps above 25C are not desirable in DWC, NFT or gravel beds running Constant Flood. The maximum possible dissolved oxygen level in the water drops away over 25C, no matter how much aeration your have. Low oxygen environments lead to root rot.

Without knowing anything about your system, there could also be an issue with suspended fines in the water, which are attracted to, and smother the plant roots.

Hi,

I have frequent root rot and fungal problems with my system when the water is very hot.

Not much to do about it except tryng to lower water temp by burrying fish tank and pipes.
You can trying boosting oxygen by adding extra air pump & air stones.
Also i've tried adding beneficial funghi like trichoderma, glomus & the like. It's not the miracle pill but it works to some extent.

Be sure to remove everything that is rotting as soon as possible because the more you have, the more it spread in your circulating water.
One last thing, these harmful funghi are boosted by high nitrate levels so be sure to have these under control.

Hope that helps.

Thanks guys, did a big cull over the last few days and added more air pumps. The system has been online for over a year and i was just thinking how nice it was to have a settled system!

My plan is to take each DWC bed offline if we cull off / harvest enough plants. Pretty sure we have some Tilapia in there nibbling the roots too and a few cracks to attend to as the pH is creeping up.

1300 ppm general hardness? That seems really high to me. I try to keep mine under 300ppm for lettuce!

Everything died except a few mint plants.

Now i'm passed the busy season for our business i've been making lots of changes. I've made my DWC beds shallower and fiberglassed the inside as i was getting pH creep from cracked concrete, along with a sloping bottom to collect solids.

I'm also in the process of splitting the fish system and plant system into two, with the goal removing all solids from the plant system.

What type of solids removal do you have? This can happen when fine solids cling to the roots and they suffocate.