nitrite in new el-natural tank? - El Natural

helenf · 05-09-2012, 09:21 PM

Hi all,

So I haven't posted here in a couple of years, I think. Haven't been doing much fishkeeping since the kids arrived...

Anyway since kid number 1 is now kindergarten-aged and starting at kindy, I agreed to set up an empty fish tank for the class of three-year-olds. It's a basic 5G tank, and I want to keep it as simple as possible, so I'm setting it up to be as low tech as I can. No filter, no heater (if I can get away with it) and maybe an airstone for aeration (it's also pretty safe for the kids, i think, since the airstone itself isn't powered and the pump can be put out of reach).

So the tank has been set up for about 3 weeks now. I put an inch of potting mix on the bottom and about half an inch, maybe a little more, of gravel on the top, and filled it with the fastest growing plants I have, including some watersprite and duckweed for the top. The tank is by a window and gets some morning sun.

I've only been able to measure the water chemistry every few days, since my daughter is only there twice a week. The first week the ammonia shot up (presumably due to the soil). I don't remember this from previous low tech tanks I've run, but I wasn't using the same potting mix, so maybe it's just that. Ammonia levels upwards of 4.0ppm. The nitrite was zero until a few days ago and now that's rising too. Today it was about 1ppm, and the ammonia is down to about 0.5ppm.

The plants are mostly doing fine, though there is a crop of algae and sludgy stuff growing too, which is why I think I'm going to add the airstone when we go in next week.

So why the nitrite? I don't remember getting much, if any, nitrite in previous low tech tanks. Is this one of the normal variations? Would you do water changes or leave it be (I can only do changes twice a week at most in any case)?

I'm a bit worried that I've promised them a working tank and so far there are no fish! Need fish in there in a couple of weeks, if it's possible.

Thanks for any advice.

Helen

corsair75 · 05-10-2012, 05:18 AM

It sounds like the tank is going through its normal cycle, albeit very slowly. As for the ammonia, it's certainly the soil that's producing it. I've had to learn the hard way myself that a little goes a long a way.

Water movement of some sort is going to be very helpful, even if it's just an airstone. In a natural tank without a dedicated bio-filter, the nitrogen cycle is handled by the plants and the bacteria distributed throughout the display. That can be a very effective combination, but it requires the water flow to distribute nutrients and deliver oxygen to the bacteria. If I had to put out a theory as to why it's taking so long for this tank to cycle, I'd say the stagnant water is limiting oxygen for the bacteria to do its thing. Water flow also counters algae growth pretty well.

An airstone would certainly help. A pump in the range in 40-50gph would probably help more. fwiw, in my 6 gallon npt I use both. I'd manually clean the existing algae, do a water change, add a pump, then wait. It should finish cycling, and you'll be on your way

Michael · 05-10-2012, 05:22 AM

I agree.

The Trigger · 05-10-2012, 05:28 AM

If there's ammonia present, nitrite is usually sure to follow it. This is completely normal. Water changes and prime will reduce the levels in the tank. Eventually it will all be converted to nitrAte and usable to your plants. But frequent water changes are the best way to reduce levels. And yes, you should at least have a small filter in there to help with circulation and clean out any debris in the water. Something about 50gph would be best as corsair said.

The Trigger · 05-10-2012, 05:38 AM

I have an elite mini internal filter on my 5gal planted betta tank with tons of plants and the water is crystal clear. I think its rated at 58gph. In reality probably more like 40-45. Think they're like $10 on amazon

helenf · 05-10-2012, 07:25 PM

Thanks for the replies.

I don't want to add a filter in there because that adds another level of danger for the kindy kids (3 year olds + electricity + water...). But an airstone, with the pump out of reach, would be safe enough, so I'll try that.

corsair75 · 05-12-2012, 10:27 AM

Fwiw, pumps are all UL rated these days. That means very safe around water. Likewise, the water in your tank is not very conductive. Pure RO/DI water insulates, marine conducts like a wire, and most f/w tanks without salt are towards the low end of the scale for moving electricity. If you were really worried, a grounding probe like the marine guys use is cheap and makes wires a non-issue.

Diana K · 05-19-2012, 09:45 AM

Use the bubbler to run a box filter.

Nitrite is a natural part of cycling the tank.
Do enough water changes to keep the nitrite under 5 ppm, the bacteria you are growing slow down when the NO2 is over 5 ppm. They grow best with more oxygen, so definitely get more water movement going.

Pretty soon (perhaps a week or two) the ammonia and nitrite will both read 0 ppm. Then you can stock the tank, but that small a tank would be so easy to overstock! Just one fish, or a couple of small ones. Lock up the fish food, or else every child in the room will be feeding the fish, and you will have a disaster.