Low nitrates - High ammonia.

[timmy]

After a year and a half in operation, all of the sudden I am not getting adequate nitrates from my system. Thought my fish effluent was not concentrated enough, but my ammonia level is high. Why is my system not converting the ammonia to nitrates...after it has been doing this conversion with no problems for about 1 1/2 years? System was thriving with beautiful tomatoes, etc...and now has a minimum of plants growing. Is there anything I'm not thinking of that may have killed my beneficial bacteria? I have gravel media beds. At my wits end...

[MattySEQ]

Tell us a bit more about the system pictures would be great aswell it could be anything from overstocked too anerobic areas

[Murray]

Agree with Matty
Suspect stale areas in the grow beds somewhere with anaerobic areas. The teltale sign is usually pH on the rise.
A completely different set of bacteria set up in those conditions, which will completely reverse the process and you will have exactly what you are describing.
You may need to give the beds a good clean out, one bed at a time.

[Wendy in BC]

I have to ask what is the volume of your fish tank, and growbeds. How many fish do you have and how big are they?

I ask because you may be dealing with two separate issues, one in the GB and another in the FT

[timmy]

Ph is 6.8 and steady, water temp 24c , beds are 10'x3'x8" and there are 2 of them on this tank, Water tank is running with 180 gal (before I had the tank filled with 250 gallons), settling tank holds 40 gallons ( no solids in the beds). I have about 60 fish, average size is 3/4 lb. I am thinking maybe I was over powering the system now that the fish are bigger and I have fewer plants at this point than I have had in the past? Also it seems the fish are not eating as much? Nitrates are around 20. I will update more with pictures.

[krizz]

Murray mentioned a good cleanout of the beds. Does this include a thorough washing of the media? I seem to have a similar situation with consistenly high ammonia and low nitrates.

[Murray]

Beds can become blocked or contain stale areas which will become anaerobic. Using too small medium is a common cause of bed difficulties. Not enough grow bed to fish load and so on.

If you are the kind of person who pushes the limits then you need to add a decent filter into the loop to give your system a chance, clean your beds one at a time and go again.

Get back to basics and make sure everything is in balance.

[krizz]

Timmy, what is the source of your water? For what it's worth, I am/was having similar problems to yours with high ammonia and low nitrates. After loosing three more fish this weekend, I finally checked the ammonia content of my make up water. I was trying to be economical and was using the condensate from our home air conditioning system. Turns out the condensate was running about 4 ppm ammonia. I am changing out the water and have seemed to notice more activity and increased appetite in the remaining fish.

[Wendy in BC]

for our Australian friends that's 60 X 340 grams fish
1274 litre growbed assuming there are 2 growbeds with the dimensions mentioned
682 litre fish tank
151 litre sump

[timmy]

Water suppy is filter house water. I have changed my water out as well. Ammonia is now .25, nitrates 0

[theNEWT]

I have seen a youtube video suggesting keeping worms in the grow bed helps reduce the likelihood of blocking as described above. Maybe that might be a possibility in avoiding future problems.

[Aquaponeer]

i see worms taking out all kinds of things in my GB's.

including sliding up on the walls of the GB to eat X, Y, Z and then back down again! love em! almost as much as my fish ^__^

[RupertofOZ]

Yep... worms are the secret weapon of media grow beds...

[Walks-In-Storms]

I've just ordered 1000 red worms (digging in fields around here produced not one worm - no insects, either; none). My grow beds (two) are sixty gallons (223 liters). How many worms should I put in (I'll use the rest in my raised bed dirt gardens).

[RupertofOZ]

Throw a handful into each grow bed...

[Fishdood]

Some observations from what I have read on this forum.

GB's may be a bit shallow....to many fish (or not enough GB's).........not enough plants.

If the fish are now producing ammonia quicker than the system can handle.....stop feeding fish and cook up a few.

[Walks-In-Storms]

Rupert & Fishdood, thanks for the help. The worms just came, so I'll follow through.

[Walks-In-Storms]

Rupert, in they went and they disappeared so fast they must have fins. Amazing, and the same happened when I put others of the batch in my raised bed soil gardens. Who would have thought worms were sprinters?

[Walks-In-Storms]

Well, it looks like "I've put my foot in it" - used galvanized stock tanks and now a second batch of fish are dying (the first batch killed by 114 degrees heat last summer), that with water pH and the rest all perfect and temperature ideal. @#$%&! (sorry, ladies). I'll have to wait until all the fish die in order to install a PVC or other pond liner in the fish and grow bed tanks, but in the meantime I'm curious: has anyone ever heard of chemical means by which the situation might be handled? What is it exactly that galvanized tanks do to the water?

I'll go to academia - the local college chemistry department - of course, but in the meantime someone here might have an idea that would help (maybe I wouldn't lose ALL the fish).

[RupertofOZ]

What is it exactly that galvanized tanks do to the water?


They leach Zinc... which is toxic to fish... and cumulative....

It's also quite a "soft" metal... dissolving readily, and due to the recirculating nature of AP.. accumulates in the fish...

[davidl]

I agree with RupertofOZ, any zinc or galvanised metal that comes in contact with the water will leach zinc in to the water and will be bad for the fish.

The only thing to do is prevent any galvanised metal or zinc from touching the water, and do very regular water changes to discard the water with the zinc in it. You can get pond liner plastic sheets or even some sort of pond rubber paint type stuff to shield off the galvanised metal.

[Walks-In-Storms]

Thanks for the help. I've started changing water regularly, draining and replacing one-third; and the fish have stopped dying (and that after only two changes). Chemistry is stabilizing (at the moment, anyway), with pH just about perfect (7.2), ammonia at about .25ppm, and nitrate at 20ppm.

I'm shopping for a tank liner, and as soon as the budget permits (my pretty girl went out the other day and came back with a new car - completely by way of surprise), I'll put it between the fish and the tank. I think I'll do the same with the grow beds - or buy some of those "IBC" "totes." That looks like a great idea to me (some of the guys' - threefiftyseven and yourself, for instance - ideas have me green with envy).