Trouble Shooting

[Paul Sommers]

• Hello All, I'm new to aquaponics and a teacher. I have a small, flood-drain system for my classroom - 70 gallon growbed, 50 gallon tank. It's for educational purposes. There are 10 fish in the tank, ranging between 4-6 inches. My pH (6.0) and nitrates (5ppm) are very low, plants grow a bit and then die off. Any ideas? Do I need to "re-cycle" my system?

• Forgot to mention, my system is currently outside in my backyard in MN - just moved it there last week.

[Kent Evans]

Paul,

What is your water temp. ammonia and nitrite numbers?

[Paul Sommers]

Temp is around 70, nitrite zero, ammonia .5

[Vlad Jovanovic]

How do you know that your pH is at 6.0 and not below that number? I say that with the assumption that you have an API test kit that only registers to 6.0 (so below that value you have no way of knowing where you're at). 

Nitrifying bacteria quit functioning around 5.7 or so. Also, their ability to oxidize ammonia becomes severely stymied at a KH below 40...

[Paul Sommers]

Thanks for insight, what do you suggest is my next step?

[Paul Sommers]

Should I try to re-cycle the system?

Paul Sommers said:

Thanks for insight, what do you suggest is my next step?

[Vlad Jovanovic]

Oh god no, just raise your pH up into the readable range IMMEDIATELY. Don't use eggshells or shell grit right now because they are very, very slow acting. Use a (non-sodium) hydroxide like either potassium hydroxide (KOH) or calcium hydroxide (AKA builders lime, pickling lime, hydrated lime, slaked lime)...just don't over do it hydroxides are pretty strong.

if you want to you could use also use potassium bicarbonate (KHCO3) it's fast acting and harder to "over do it'.

Paul Sommers said:

Should I try to re-cycle the system?

Paul Sommers said:

Thanks for insight, what do you suggest is my next step?