Dizar

8 month old system ammonia nitrite problems

2 posts in this topic

Hi guys,
I'll start describing my system:
500 lt IBC fish tank
1 grow bed 100x120x25cm (300lt). Wet media probably 200 lt
Media expanded clay pebbles.
Water runs 15 minutes every hour using a timer.
I'm growing 2 broad beans, 1 lettuce 1 strawberry 1 pok choy.
15 trouts weighting 80ish grams each.
Current feeding 10gr daily (divided in 4 feeds) and I should be feeding 25gr per day.
water temperature have been quite low, between 5 and 20 degree

I've been running this system for 8 months, they cycle was completed in the first month.
Generally speaking I've seen nitrates the first month and never anymore.
With this feeding rate my ammonia and nitrites levels are always quite high, around 1ppm.
If I stop feeding ammonia and nitrites disappear within 2 days.
Yesterday I cleaned the grow bed but it wasn't dirty or smelly at all.


I know 15 fishes are too many for my grow beds and I'm planning to add one more but shouldn't my current media fully support my current fish weight and feeding rate? If that is so, why I'm seeing ammonia and nitrites at 1ppm (and even more if I feed more)
Also, why i'm not seeing any Nitrates with those few plants?

Thanks guys in advance and, very nice forum.

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Hi Dizar,

Ammonia should be kept at a trace.

There are charts around you can use as a useful tool to indicate toxicity of your water.

I do not recommend cleaning your grow beds at this early stage, you may have "washed away" your good bacteria and maybe your system is doing a "mini cycle" to catch up so your ammonia may be spiking. If it is, your ammonia should rapidly come down after a day or so.

The aquaculture people here can help you with your calculations for FCR but as a backyard hobby person I would aim for at least, if not more, equal (500lt plus) of "wet media" to fish tank water.. I would also add filtration to your system. I like a combination of a MBBR and a radial flow filter.

I found 18C to be the "sweet spot" for running rainbows but do not be concerned if the temp drops down...Remember where they came from?

Cheers.

 

Edited by bigdaddy (see edit history)

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