methane?

[amwassil]

As I've recounted in another post, I just lost a Dwarf Gourami in a 10 gallon aquarium, I suspect due to methane poisoning. I had replaced a TLF 550 reactor using Seachem Matrix as the medium with my two Drop algae scrubbers. The TLF reactor had been filtering that tank for about 2 1/2 months and both fish had seemed OK, although I had been replacing water daily to remove the nitrates.

I had placed one of my Drops in the tank and it had been operating for about a week along with the TLF 550. Nov07, after cleaning both Drops, I put my second Drop in the tank and removed the TLF reactor. Everything seemed OK, but by Nov09 the water had become cloudy (white) and there was a lot of debris floating around, so I cleaned and sterilized an idle Eheim 150 canister along with some coarse and fine sponges and added new floss. I changed a couple gallons of water and put the Eheim on the tank. The water cleared within a couple hours.

Nov10 the water was cloudy again and both Gouramis showed signs of stress. I should have pulled them both out then, but I didn't. Instead I changed a couple gallons of water. On Nov11, the water was cloudy again and I noticed what seems like a methane odor. I changed a couple gallons of water, but the female died that afternoon. After she died I pulled the male out of the tank.

I added a bag of Seachem Purigen to the water. By the end of the day the water was clear again. By the next day the odor was reduced quite a bit.

So what I have now: two Drop 1.2x, the Eheim canister and a bag of Purigen drifting around in the tank. The Drops are growing algae because small pieces of algae float around the tank until getting sucked into the Eheim intake hose; I will clean them tomorrow and find out what exactly is growing in them. The pieces floating around look like green hair algae. The water is clear, but still has a faint odor of methane. So it seems that the Purigen is removing the most of the methane but not all of it.

Water params: pH 6.0, ammonia 0.0, nitrite 0.0, nitrate 0.0. Note: I added a liter of water from my main aquarium yesterday to feed the algae. That bumped the nitrate up to about 15-20ppm. Also, in the week that both Drops have been in the tank, the pH has dropped from 7.0 to 6.0. Would methane cause that?

Now to determine where the methane is originating. Anyone have any ideas??? Thanks.

[SantaMonica]

I doubt it's methane, since it has no odor. Maybe you mean hydrogen sulfide. But there was some type of bacterial bloom, from an ammonia source somewhere, perhaps a deep sand bed, or anything that was buried and then opened/dug up.

[amwassil]

Thanks. I'm fairly confident it's not H2S. I know the 'rotten egg' smell of that. The odor is more 'earthy' like you'd find around a stagnant pond. A lot like wet dirt. The white/gray cloudiness made me think it might be some kind of bacterial bloom. Maybe it's gone away because it's eaten whatever it was eating to cause it. I'll be cleaning my drops tomorrow, so I'll see if anything ugly is growing in them. The Purigen, I presume, is keeping the odor down quite well. It's still detectable if I stick my nose in the tank, but it's quite faint. There are two apple snails in the tank and they don't seem to have been bothered by whatever it is/was that nailed the fish.

[SantaMonica]

The earthy smell usually comes from the water level that has dropped, causing the top layer of glass algae to die.

[amwassil]

The earthy smell usually comes from the water level that has dropped, causing the top layer of glass algae to die.

Thanks, that's good to know. The water level does vary slightly up/down in that tank. There is still a very slight odor and it resembles the odor inside the drops, ie algae.

Good news is, I cleaned both drops and there was nothing growing in them other than algae and not much of that. With nutrients very low in this tank, I can understand why the algae is not growing much. However, look at the water params I just measured:

Nov14:
1. pH: 6.0
2. Ammonia (NH3): 0.50
3. Nitrite (NO2): 0.0
4. Nitrate (NO3): 20

Two days ago I added 1 liter of water from my main fish tank to feed the algae some nitrates. So that's where the nitrate is coming from. I did not measure NH3 in the added water at the time because I had no reason so suspect it contains any. I just tested now and the NH3 in the main fish tank is 0.0. So I don't think I added that ammonia along with the nitrate. There are currently two apple snails in the tank and nothing else. I have to conclude that those two snails produced the NH3. Yet I'm rather surprised that the algae didn't consume it. I measured params on the 12th and NH3 was 0.0, and it had been 0.0 each day since Nov07 when I started measuring it daily. So I'm rather confused as to what's going on in this little tank. The algae doesn't appear to be eating either ammonia or nitrate. I've had the drops on 15/9. Any ideas?

[SantaMonica]

Well the scrubbers need to be growing to absorb. Put them on 24 hours, and see how it develops.

[amwassil]

OK, I'll try that as of today. 24 on for a few days and then I'll peek inside. Thanks.

This occurred to me. When I removed the TLF reactor from the tank there were very low nutrients in the water, only a small amount of nitrate and whatever ammonia the two little fish were producing which the algae consumed over the course of a couple days. Is it possible that whatever nitrifying bacteria in the tank died and some type of heterotrope started to eat the dead bacteria and produced the cloudiness. The heterotropes then ran out of food and they died next. Along with dead bacteria there was dead 'glass algae', hence the odor. Is that plausible?

[SantaMonica]

If you stirred up the substrate, that probably just put a lot of organic particles into the water at once. That would allow more surface area of the particles to be exposed to the water. So you would probably smell that, and maybe it also allowed bacteria to multiply more too.

[amwassil]

This is a 10 gallon bare bottom tank. I siphon out debris every day.

I measured NH3 (Nov15, 1:30 pm) a couple hours ago and it's down slightly from yesterday's reading. As per your previous post, I did not turn out the lights in the scubbers. So maybe the solution here is to run the lights longer. I'll wait until next weekend and report on water params and algae growth. If the longer lights-on time is the solution I expect some algae growth and water params to zero. I'm still wondering about the pH falling.

[amwassil]

Nov21 Water params:

1. pH: 7.0 (Note: I added baking soda on Nov18 to raise pH to 7.0 and it has stayed there with no additional soda)
2. Ammonia (NH3): 0.0
3. Nitrite: 0.0
4. Nitrate: 20.0+
5. Phosphate: 2-3+

I have not changed any water since Nov11, although I have added about 500ml to keep the water topped up. I pulled out the Purigen bag on Nov16 since the cloudiness was gone. The cloudiness has not returned and after removing the Purigen the odor decreased a bit more. So I guess the Purigen odor was part of the issue with that. There is still a bit of odor, but it doesn't smell like anything bad. I started measuring Phosphate on Nov18 and it was 5.0, so it is decreasing. My guess is the algae is eating the ammonia and phosphate first because it hasn't reduced nitrate since I added it more than a week ago. The algae started growing again on Nov19 after I added baking soda to raise the pH. Here's today's growth before cleaning. You can't see in the photos, but there is algae growing on the bare plastic inside of the doors. It commonly did this when the drops were in the big fish tank.

6311 6312

I also added some snails. There are now two large, two medium and one very small apple snails in the tank.

Since the algae started growing again, I went back to lights 15on/9off.

[SantaMonica]

The soda probably just helped the Alk, which is consumed by algae when it grows fast.

Also, the growth on the plastic can happen with slime types of algae like is currently growing, because there is no strong pull on the algae. But as longer Spirogyra hairs attach, they will not be able to hold on to the bare plastic.

[amwassil]

Nov28 Water params:

1. pH: 7.2 (Note: I added about 1/4 tsp baking soda on Nov23 to account for additional water added to keep the tank topped up)
2. Ammonia (NH3): 0.0
3. Nitrite: 0.0
4. Nitrate: 20.0
5. Phosphate: 1
6. dKH: 4 (~70ppm KH)
7. Calcium: 380ppm

I have not changed water since Nov11, although I have added about 500ml this week to keep the water topped up. Nitrates have not decreased measurably yet, but phosphate continues to decrease. I expect phosphate will hit 0.0 before next weekend and hopefully the algae will start eating nitrate. The algae grew much thicker this past week than previously. So it looks like maintaining pH at 7.0 or above is good for the algae.

6315 6316


The soda probably just helped the Alk, which is consumed by algae when it grows fast.

I've also started measuring dKH and Calcium. I supplement calcium using white chalk sticks. The snails are much more active now with the increased pH and calcium.

[amwassil]

The initial issue of this thread seems to have resolved itself. There is still a slight odor, but it does not smell noxious at all any more. The snails seem quite happy. I am not going to put my Dwarf Gourami back in the tank, though, until the nitrates is below 5.0. Anyhow, I copied my above post of today to my original log post for my 2 drops. I will continue to report on my periodic water tests in that thread.