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Foul odor from newly planted 20G

2K views 29 replies 9 participants last post by  mossman77 
#1 ·
I've noticed a strong foul odor coming from my 20G acrylic tank the past several days. I've had plants in this tank before and it has never smelled like this. Last Friday, I added a bunch of new plants, which are adjusting to my water (i.e. melting). Could the smell be from the plants decaying? My other planted tanks have never smelled like this, so I'm a bit confused.
 
#3 ·
There isn't much visible die off to remove. Everything looks pretty good actually. I have a couple large Nerites in the tank. Maybe one of them is dead and that's what I'm smelling? Except I'd expect my Congo Tetras to make a quick meal out of a dead snail.
 
#5 · (Edited)
Hmm, not sure I would expect that. At this point nothing to do but find the cause. An aquarium should never stink. Have a mild earthy smell when your nose is right over maybe, but never a foul odor. Something is decaying and needs to come out.
I planned on rescaping that tank anyway, so I guess now is a good time.

My bottle of Prime smells like rotten eggs, so I'm sure adding that to the water isn't helping.
 
#6 ·
All dechlorinators use sodium thiosulfate and will have that odor in the container. Shouldn't be enough going in the tank to cause any problems though. I'm betting you find a dead snail and this will be over shortly. Pro tip- do not use your hand to remove the snail. That stink is hard to wash off.
 
#10 ·
Did you add any plants with bulbs? The bulb might be rotting and releasing a rotten egg smell. Try adding new activated carbon to the filter to remove the odor. I suspect something is rotting under the substrate. Remove any dead roots or bulbs. Increasing circulation might help. If using well water you might have hydrogen sulfide gas seeping into your water supply, but the toilets and sinks would also stink.

I've had snails fall out and die behind my tank without realizing they were missing. A dead snail is the worst thing I've ever smelled in my life. Took a day for my fingers to stop stinking even after bleaching and scrubbing them clean. Don't touch dead snails with bare hands. Use a bag and beware that the body might fall out of the shell if tilted the wrong way. You don't want that happening inside the tank or on the floor.
 
#12 ·
I'm using Eco Complete, which has been in there over a year. It's hard to say what it smells like. It just isn't a normal fish tank smell. My other tanks smell earthy, but this one is more pungent as of the past several days. The only thing that has changed is adding a bunch of plants and dosing with NilocG Thrive C. I add NilocG Thrive C two times a week (and just started to last week) and feed blood worms and flake food. Parameters are 0/0/15/7.5/4/4/80 (Ammonia/Nitrite/Nitrate/pH/gH/kH/Temp).

Several of the plants are melting now that I look closer, so maybe that's it.
 
#14 ·
So the tank started emitting an odor around the same time you started using a liquid fertilizer?

And plants started to melt around the same time, as well?

I added a bunch of new plants last Friday (there were no plants remaining from the previous planting) and started dosing with Thrive C at the same time. The plants are starting to melt, as expected. The tank used to be planted and I've used liquid ferts before (Aquarium Coop) and never had this smell. I suppose there could be some residual plant matter decaying inside the substrate from the old plants, but I thought I got most of it out. I planned on rescaping anyway, so I may remove the fish and redo the entire thing (meaning remove all the old substrate and replant with same plants).

Bump:
Did you add any plants with bulbs? The bulb might be rotting and releasing a rotten egg smell. Try adding new activated carbon to the filter to remove the odor. I suspect something is rotting under the substrate. Remove any dead roots or bulbs. Increasing circulation might help. If using well water you might have hydrogen sulfide gas seeping into your water supply, but the toilets and sinks would also stink.

I've had snails fall out and die behind my tank without realizing they were missing. A dead snail is the worst thing I've ever smelled in my life. Took a day for my fingers to stop stinking even after bleaching and scrubbing them clean. Don't touch dead snails with bare hands. Use a bag and beware that the body might fall out of the shell if tilted the wrong way. You don't want that happening inside the tank or on the floor.

They are all stem plants (if that's what they're called), so no bulbs. I'll add carbon as suggested. Circulation is excellent, so that isn't it (canister with up to 10x turnover per hour). I'm on city water and my other two tanks don't smell at all.

I'm using Thrive C in all three of my tanks, and this is the only tank that smells, and the only tank with new plants (15 of them).
 
#15 ·
Rescaping will probably clear things up for you, since that's the route you want to go. And it does sound as if new plants are part of the problem.

Doubt it has much to do with your substrate, as it's inert.

While you didn't ask for any advice on the fertilizer front, it's going to be exponentially cheaper for you to buy dry fertilizer salts when you run out of the liquid you've got. They're easy to mix up. $8-$10 worth of dry ferts will last you several years. May be worth considering when the time comes.
 
#16 ·
While you didn't ask for any advice on the fertilizer front, it's going to be exponentially cheaper for you to buy dry fertilizer salts when you run out of the liquid you've got. They're easy to mix up. $8-$10 worth of dry ferts will last you several years. May be worth considering when the time comes.
I've looked into dry ferts in the past, but it started to sound complicated, so I opted to go with an all-in-one liquid fert. If you can recommend some literature on the subject, I'd be interested.
 
#17 ·
Check out any fertilizer calculator or the fertilizer section here on the forum. Tons of threads of members discussing what they put into their mix. Everything from low-tech to high-tech EI dosing. Find a thread from someone with a tank you like and mimic what they do with ferts. That's the easiest way.

Keep the bottle you've got now and reuse it if you give dry ferts a shot.

Since you're not dosing a high-tech setup, it'll be way easier than you're imagining and $10 worth of ferts will probably last you a decade.
 
#18 ·
Okay. Thanks.

In reference to the spot algae, it is proving difficult to clean off with my algae scrubber pad. Does a credit card work better, or would this scratch the acrylic? Once the fish are removed and tank is empty, could I soak the scrubber with some H2O2 or Seachem Excel to help dissolve it?
 
#19 ·
Green spot is difficult to remove from glass, I can only imagine tackling it on soft acrylic. If the tank is going to be completely empty for a few days, I might be inclined to try a paper towel dampened with household bleach and let it sit on affected places for a few hours. This can be followed up with a vinegar scrub to help neutralize the bleach, then rinse very well. I think peroxide or glut is going to take a loooong time to kill it all. FWIW, after setting back up, monitor your PO4. I've never had green spot appear in any tank of mine where that nutrient wasn't low.
 
#21 ·
The spot algae issues just started appearing after I got a new more powerful light. Guess I should decrease the intensity a bit until the plants are done melting and sprouting new growth.


I have essentially no PO4 in that tank, and have used Phosguard in other tanks to bring levels down because it was my understanding that excessive phosphate leads to algae. Apparently that's a falsehood?

Bump:
More than likely, especially with eco complete, you’ve unearthed a hard anaerobic pocket in substrate. That smell is probably why your plants died to begin with.

Keep seeing this same problem with Eco, to coarse, detritus settles into lower layers, cuts off circulation. Lower layer goes foul.

How much circulation do you have in tank? You need at least one small jet pointed down at substrate to keep it saturated with oxygenated water and keep aerobic activity up.

Makes sense. However, the old plants have been dead and removed for months. There were only a couple S. Repens remaining, which I removed last week when I replanted. But that doesn't mean I didn't unearth a pocket while I was replanting.


Circulation is very good. I'm using a canister rated for up to 55 gallons (200 gallons per hour turnover), and the plants are moving from the current.
 
#20 ·
More than likely, especially with eco complete, you’ve unearthed a hard anaerobic pocket in substrate. That smell is probably why your plants died to begin with.

Keep seeing this same problem with Eco, to coarse, detritus settles into lower layers, cuts off circulation. Lower layer goes foul.

How much circulation do you have in tank? You need at least one small jet pointed down at substrate to keep it saturated with oxygenated water and keep aerobic activity up.
 
#22 ·
Like @somewhatshocked said, I doubt it is a problem with substrate as it is inert.
I have a lot of Eco-complete in various tanks atm ( my 180 gallon, my 60 gallon) and have used for many, many years --- I have never had any problems with anaerobic pockets. I think that issue, of anaerobic pockets in general and in circumstances with eco-complete specifically is far more rare than the attention it has been given of late.

If you are looking to replace substrate, however, no better time than the present.
 
#25 ·
I would say don't starve your fish for any reason! And yeah, you'll want to test your nitrate to see where you want it. Roughly 10:1 NO3:pO4 ratio is called for but I don't pay much attention to that. About 1 PPM should do if NO3 is present. I think we might be getting to the bottom of why so many of your plants are melting.
 
#28 · (Edited)
It was my understanding that melting is normal when planting new plants, due to a lot of plants being grown emersed up until they're purchased.

In addition to the output nozzle, I have a surface skimmer, which pushes water back into the tank with significant force. Trust me, there is plenty of flow. The plants at the bottom are swaying.
 
#29 · (Edited)
Here are a couple pics. You can see the new plants dying off, which is what I believe I am smelling. The more I smell it, the more it smells like decaying plant matter. The algae around the substrate was non-existent prior to getting a new light and dosing with ferts. As of yesterday, I've decreased the light intensity and switched to a 5-4-5-10 schedule (on-off-on-off).

These are the plants I have, and the state in which they were raised prior to purchase. The Heteranthera has the most significant yellowing/die off/melting, and the Microswords have some as well. All the others appear fine. I read the Heteranthera likes at least 10ppm of nitrate. Otherwise it will yellow and melt away. My nitrate is typically around 15ppm or more, so I don't think that is the issue. I'm guessing it needs some time to adjust to my water.

Grown ABOVE water:
- Juncus Repens (middle foreground)
- Golden Jenny (right foreground)

Grown UNDER water:
- Mayaca (left background)
- Heteranthera (right background)
- Micro Sword (left foreground)

(Two small Amazon Swords--harvested from my daughter's 29 gallon--are also in the tank to the left of the Golden Jenny)

Pics taken last night (the light looks purple/blue because I decreased the white intensity for the evening):
 

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#30 ·
I cleaned the tank and did a large water change (nearly 75%) yesterday and things are looking much better. The smell isn't as pungent. I'm starting to get a little bit of new plant growth, but nothing very noteworthy. Still a lot of melting going on, but new growth emerging at the same time. The Heteranthera is melting the worst, but has some new growth at the tops. I would like to trim this plant down low though, because it supposedly gets thick and bushy, but I'm hesitant to do so at this point. Should I go ahead and trim it down now, or wait? I'm concerned that if I wait, it will become too leggy, but I'm also concerned that if I cut it now, I will kill it. What if I trimmed them and planted the cuttings into the substrate? I see a lot of root growth along the stem, so it would presumably take hold and grow.
 
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