Gas buildup in gravel - advice

[Codefox]

I was visiting my parents this weekend and I took a look at my mom's fish tank. Its a 20g hex tank. It was a birthday gift for her back when I was in high school. She's really pretty good about following my instructions on adding fish and feeding them and because of that she has always had a decent survival rate for her fish (she loves her fish but does basically view the tank as decoration)

One thing I could never get her or my dad to do was do a PWC or use a python/gravel vac. As a result, they have a very deep tank that gets topped off with fresh water continually. Besides having a tank that's ripe for old tank syndrome (I'm scared to see her water parameters...they must not be too out of whack because new introductions don't die)

When I was at home this weekend though, I took a look and I saw there was gunk in the gravel. I'm guessing anaerobic bacteria colonies. There were large pockets of bubbles forming in there too. Honestly I don't think it would take much for one of those pockets to suddenly errupt from the gravel. A vacuum bumping the stand could trigger it I'd bet.

I know if I tell my mom about the danger the tank is in, she would take me seriously and do something about it. But I'm concerned that doing a water change now would likely cause an ammonia spike. And I don't know how to safely remove those bubbles from the tank because just using a python now would do nothing except release all of that gas into the water. I don't know what the bubbles are but given the age of the tank I have to guess its toxic.

What's the safest way to do this? Removing the fish temporarily and doing a full water change seems like the only way to remove the gas but the shock of all that clean water would probably kill the fish anyway. It seems like a catch-22 at this point.

 

[Lonewolfblue]

Depending on how large the pockets are, could ease the gravel vac in and allow the gas to erupt in the gravel vac using the python to completely remove it from the tank. Once you get the ones that are visible, go through the gravel cleaning it all out.

 

[Codefox]

They're big. From what I could see along the side of the tank, it appeared that the entire gravel bed is filled with the gas...top to bottom.

 

[Lonewolfblue]

Sounds bad, lol. May just have to break them up anyways. Not sure if this would work, but use a plastic container submersed, and break up large sections at a time and taking the container to the surface, trying to protect the fish as best you can. Or fill a bucket with tank water, place the fish in the bucket, and then just clean it as best you can. That's probably the safest way. And have some ventilation, lol. Don't want it to knock you on your butt, lol

 

[afishyonados]

You could drain out the tank water into a holding vat with the fish. Then refill the tank with pre-treated water. Then vaccuum out all new water, vigorously siphoning detritus and gas. Finally replace the old water and the fish. Next week, do a normal water change.

 

[Codefox]

I won't be down there again for about 2 months I think. Given that the tank has existed like this for a few years...I think in two months nothing should be different and I'll be there for a long week during Thanksgiving. It probably will take a few days to take care of the tank. Here's what I'm thinking :

I'm having my mom take her water in to get tested for Ammonia & pH levels. If she has a low pH and high ammonia which is what I suspect, then I can't just change the water. If she's lucky, old tank syndrome hasn't set in but I doubt she's lucky on this one If it is the case of high ammonia...doing a water change will just make it all toxic as the pH comes up. I'm thinking of first conditioning the water with a heavy dose of Prime to eliminate the ammonia...this way there won't be anything to release into the water

I'll be down for a week so I'm thinking maybe a 15% water change every other day? After 3 water changes over a 6 day period, that should make the water at least safe to work with. Or do you think that's too fast? I'll be down 9 days so I have some time to work.

Once the water changes have brought the tank water at least reasonable, I would transfer a large amount of water (maybe 10 gallons) into a QT tank and put all of the fish in there. Then I'd go ahead and just completely drain the rest of tank, siphoning the gravel out completely. Then I could go ahead, and refill the tank with 1/2 new water and 1/2 tank water.

Is this all too fast though for the fish? I'm guessing there will be losses anyway but not as bad as if this is left unchecked.

 

[Lonewolfblue]

You should be fine with that. I don't see much problems other than old tank syndrome hitting before you get to it.

 

[Codefox]

Well, I can't see what would trigger the ammonia being released before I do anything. I may have her add Prime herself just to kill that bird. The only concern is that gas being released before I can do anything...which of course there's nothing to do but hope that after four years...two more months won't matter!

 

[Thebluyak]

hmm mts would help stir those pockets for the future

 

[krap101]

could gas really build up to that point with gravel? when i had gravel id get the occasional bubble, but that was it.

 

[Lonewolfblue]

Also, as for the gas, I can't remember what it is but the gas itself isn't ammonia. The ammonia is from the fish pee and ppo, and anything that's decomposing, but the anaerobic bacteria produces I think hydrogen sulfide? Or something like that. That's what could kill the fish. Someone correct me on the gas, as I can't remember exactly what it is.

 

[Codefox]

No, the gas is Hydrogen Sulfide. I just know there's a lot of issues that have built up with this tank which is why I have to take care in how I solve them. And we're talking 4 years with no water change ever. That's why the bubbles are like that and why the tank water is like it is.

 

[JohnPaul]

Hydrogen sulfide is nasty for two reasons, not only is it quite toxic (and it stinks to high heaven also), but it can also mess with pH, as it is rather reactive in the acid-base realm.

A short term solution (or, gradual solution) would be to put a few MTS in the tank. As they slowly move through the substrate, they will release the H2S very slowly. At the same time, they will be consuming the detritus on which the bacteria are feeding, and also (I have heard, at least) consuming the bacteria themselves.

As long as the tank doesn't have any loaches or puffers, a few MTS could go a long way towards solving the problem. And since they spend the daylight hours buried, they aren't likely to be a big "eyesore" like other snails might be in a tank.

 

[7Enigma]

I might be wrong, but old tank syndrome is not a buildup of ammonia in the tank (this would kill any fish regardless of age/health), but rather a buildup of very high nitrAte levels. The nitrifying bacteria take care of the ammonia and nitrIte, but then without plants/PWC are left with a tank full of nitrAte.

MTS is a good idea, however, if the degree of gas buildup is as much as you say (I've seen this before as well in some tanks and virtually ALL of the gravel seems to be "floating" in air) the MTS will most likely kill themselves and rot in the tank as well. I think this is definately the time for a big change in the tank.

You need to determine the nitrAte levels in the tank and begin small water changes if the levels are high. Anything quick very well might harm the fish, but just tell your parents to start with a gallon a day water change. Shouldn't take more than 2 minutes to take out, match temp, add a little Prime, and back in the tank. That way you know you are reducing the dissolved organics, but at a slow enough rate that your fish shouldn't be affected.

Might also be smart to introduce anacharis or other nitrAte sponge plant. The light level won't matter (just float the plants), and you'll have a very high likelihood of introducing some pond snails, which if your parents don't find disgusting, will begin to multiply like crazy helping to rid your tank of bacteria...

 

[Codefox]

Old tank sydrome is a lot of things, aided by the high nitrate levels. As nitrate goes up, pH will go down. Nitrite has to be formed by stripping the nitrogen from the ammonia...leaving only hydrogen ions to acidify the water. As the pH lowers itself over time the ammonia eating bacteria is eventually inhibited from doing its job and the ammonia builds up. Its not as serious at a low pH though because a lot of ammonia is converted to (relatively) non-toxic ammonium.

As its been literally 4 years of no water changes, I would guess the pH is pretty low. (Especially since they use bottled water...its starting off at ~7.0 instead of our higher pH tap water here in Florida) I'm almost afraid of what it is. Any water changes now have a risk of severely upsetting the balance in that tank. But I'll handle that in a couple months when I go back down there. After 4 years if nothing is done for a couple more months, I don't forsee anything really changing.

As far as plants, nah. Its a deep tank with poor lighting. Even the hardiest plants would have a rough time surviving their tank.

And I think there's something wrong with your A & I keys.

 

[7Enigma]

Interesting, didn't think about those effects after such a long time. I still think a 1 gallon (5% PWC) would not have much affect on the tank conditions and would slowly bring the tank into better parameters.

And I use the A and I for emphasis because I often see people writing the wrong letter and others (especially newer members) that are trying to understand the cycle get confused. This way I can emphasize the letter so its clear we are talking end of cycle (low toxicity), or mid cycle (highly toxic).

 

[Zagz]

I agree you should do nothing until you know the levels in the tank. I'd suspect the nitrate is quite high. Once you know the levels you can deal with the gas issues appropriately. You obviously are quite well aware of what a sudden change in parameters will do to the fish.