low oxygen

[Baos]

Ok, so I bought a red sea o2 test kit to verify a hypothesis I had. Tons of beneficial bacteria can be a bad thing. No foul odors from my aquarium. Everything perfect. Ammonia, Nitrite, Nitrate test 0 in a planted tank. In my tank I currently have a surfact skimmer, an air bubbler about 30" long, and a modified eheim 2017 to make a small waterfall on the way back into the tank. My readings are 3 drops and blue, so 3ppm oxygen if I am reading it right. My temp is about 77 F which means I should have 8.3 ppm oxygen. I've also noticed some panting on the fish. I usually do a water change and they're fine for a few days. apart from trying to get rid of the beneficial bacteria living in my substrate which unfortunately needs some biological processes how should I go about adding more oxygen? It's a 90 gallon planted tank with breeding and some young fish.

[Baos]

I found a chatroom and with the advice of a guy in there I took an air tube, hooked it to a cheap powerhead from walmart and made a venturi powerhead. hopefully it helps =)

[werner]

How heavily planted? CO₂ addition?

[jvision]

Along Werner's thinking, if it's heavily planted, start adding CO2 and ferts. Your plants will saturate the water with O2. Of course, you'll have to change out a couple filters (the waterfalls and bubbling will gas-off your CO2). Using the CO2 chart (Google will lead you right to it), you should aim for about 30ppm CO2 - with adequate fertilization, you'll have 100% O2 saturation in no time.

[Baos]

Rather heavily planted. enough to provide hiding spots in the plants. No co2 addition though. It's a little more pricey than I can go right now. I should also mention that my substrate bubbles with co2 which was the effect I was looking for, but to suck up all the o2 is overkill.

[jvision]

Maybe I missed something... You're not adding CO2, but you have CO2 bubbling from your substrate? Maybe you have an airline going below your substrate?

Or are there bubbles coming from your substrate w/o adding an airstone/bubble wand? If that is the case, that's not good - it could be NO or SO2 gas, which is deadly to fish.

[werner]

Given that it's heavily planted, you probably don't have the "tons" of bacteria in the substrate (or filter) that you think you have. The plants will be using most of the ammonia/ammonium, so the numbers of bacteria will be significantly smaller than would develop in a fish-only tank.

If you have low O₂ levels, they are more likely the result of the respiration of your fish and plants (night). Increasing the surface agitation is the solution.

And, as jvision mentioned, the bubbles from the substrate are a cause for concern.

[Baos]

Maybe I missed something... You're not adding CO2, but you have CO2 bubbling from your substrate? Maybe you have an airline going below your substrate?

Or are there bubbles coming from your substrate w/o adding an airstone/bubble wand? If that is the case, that's not good - it could be NO or SO2 gas, which is deadly to fish.

It's a natural planted tank with black soil substrate. Unfortunately the substrate wasn't done decomposing when the store decided to sell it. There is no smell from what bubbles up so I don't think it's s02. I havn't considered NO at this point.

[Baos]

Given that it's heavily planted, you probably don't have the "tons" of bacteria in the substrate (or filter) that you think you have. The plants will be using most of the ammonia/ammonium, so the numbers of bacteria will be significantly smaller than would develop in a fish-only tank.

If you have low O₂ levels, they are more likely the result of the respiration of your fish and plants (night). Increasing the surface agitation is the solution.

And, as jvision mentioned, the bubbles from the substrate are a cause for concern.

I was told they were a good sign.

[Baos]

This is what Diana Walstad sent me.

An organic soil can consume considerable oxygen, especially first few months. For your tank, I would turn up the filter flow rate to make sure that your fish get enough oxygen. Eventually, decomposition will slow down as the fresh soil organic matter gets chewed up. Then you might want to turn flow rate down to conserve CO2 for your plants.

Its tricky finding the correct balance. Let fish behavior be your guide. If fish are gasping at the surface in early morning, then increase water flow/aeration. If fish are fine and plants growing poorly, then try decreasing the water flow/aeration.

[werner]

Ah- it's a soil substrate. That's a different thing altogether.

Since Diana Walstad is giving you advice, don't listen to us (we're not worthy!) :bow:

[Baos]

Ah- it's a soil substrate. That's a different thing altogether.

Since Diana Walstad is giving you advice, don't listen to us (we're not worthy!) :bow:

Still any ideas to up aeration like crazy could help. I think I need to get a much more powerful air pump.

[African_Fever]

Try a hydor powerhead/water pump and stick the airline tubing from your air pump into the slots on the hydor. If you're able to point it down at all (depending on plants/current etc.) it'll blow the air bubbles quite a bit further than any other powerhead I've tried it with.

[Baos]

Low oxygen solved. And odd as it is the waterfall on the left side and a bubbler wasn't enough to do it on their own. Oh and don't forget my modified waterfall that I changed back to a standard eheim as well as the powerhead that didn't cut it. The whole surface is in a constant agitated state kind of like simulating rain. I can actually watch the oxygen bubbles diffuse. I've got 5 sprinkler heads in total and have plans to add 2 more. They are powered by the 1100 utility pump that was available for $30 in the equipment section. I've noticed a ph change at this point and I havn't seen too much co2 bubbling from my substrate. perhaps I was saturated? Oh and I continue to have to dose about a cup of nitrate/week of the generic stuff I got from natures corner store. I barely have a detectable nitrate level

Edited February 3, 2010 by Baos