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Resetting a goldfish tank
February 11, 2014 7:16 PM   Subscribe

Hi everyone. This is a bit of a follow-up to my previous question. So our second and final goldfish died today (don't think this one was ammonia poisoning, was fine last night and belly up-dead this morning). I want to take this opportunity to set up the tank properly and do better by the next fishies, because we weren't very prepared for these ones a few months ago, and sort of learned on the fly. I have a few questions. (Lots of detail inside because I don't want to forget anything.)

Info about our set up:

1. We have this tank, 10 gallon, which I know (now) is only really good for one goldfish.

2. We were using the filter with a carbon insert in the cartridge (not cleaning the cartridge, just changing the carbon filter every month).

3. After the last fish death, I got the ammonia down, but then after a week or so, I couldn't get it to zero. Even with 50% water changes every other day, which is what we did if it got above 0.25 ppm. The other fishie seemed fine, until this morning. I wasn't measuring nitrites/nitrates separately, was using an API all in one kit. pH was always OK and it's my understanding that goldfish can tolerate a pretty wide pH range, with the preference to be around 7-7.5 which is what it was. If the ammonia was just barely detectable we changed 30% water every few days (I know all this water changing probably stressed out the fishie, but it was that or ammonia spikes).

4. We didn't have live plants because the store employee told me that bc goldfish like to eat veges, that was a good way to get them nibbling on them and eating (and excreting) way more than they should.

5. We fed them once every other day. They always ate the food immediately.

My questions:

1. At the moment, the tank is still sitting there with water in it, because I couldn't face cleaning it out yet. I will before bed. What is the best way to clean out? We are away next week so wouldn't be putting a new fish for a couple of weeks. Should we do a full on clean, bleach the insides, clean the decorations/fake plants and just start again then? Should we just wash out with water? Should we do not much and run the filter while we are away?

2. Do we really need the charcoal filter? I get that we need a bio filter for the good bacteria to grow on, but I'm a little confused about the carbon one. Basically we put it there bc it came with the kit. Other people seem to just use a sponge filter and rinse it every so often?

3. How the hell do we keep ammonia down? We'd had the tank for a few months, so thought it had cycled fine and nothing seems to have precipitated the first spike and fish death. But I'd like to start off right. Am more than happy to monitor constantly to keep the fishie happy, but all of the questions I see online basically end with "big water changes". What if that just doesn't work? We tried to resort to an ammonia reducer a couple of times - which I know isn't a great option - and it didn't seem to work either. We tested our tap water and it came out with a zero reading, so it's not background.

4. How often do you scrub out the inside of the tank with an algae pad? I feel like maybe we weren't doing that enough.

Would be great to hear any other insights as well! thanks, ask mefi.

(I have read all goldfish-related questions on ask mefi, understand cycling the tank, and have been reading many forums about goldfish in the past few weeks. I still don't feel like I've got a handle on these specific things.)
posted by gaspode to Pets & Animals (6 answers total) 3 users marked this as a favorite
 
1. At the moment, the tank is still sitting there with water in it, because I couldn't face cleaning it out yet. I will before bed. What is the best way to clean out? We are away next week so wouldn't be putting a new fish for a couple of weeks. Should we do a full on clean, bleach the insides, clean the decorations/fake plants and just start again then? Should we just wash out with water? Should we do not much and run the filter while we are away?

Since you don't know why the fish died, you might find it easier in the long run to just break down the tank and do the (diluted) bleach/rinse thing. While the tank is empty, if you want to really scrub at it, (the original) Mr. Clean Magic Eraser is fine for tanks. If you want to keep the bacteria colony you have going, in the very short term, you can put some of the substrate/gravel or a piece of decor in a bucket, refill the bucket with dechlorinated water, and put in an airstone to keep the water from going stagnant. The only thing that I think you for sure have to throw out is the filter cartridge, because you don't know what it might have picked up from your fish and it's impossible to really clean in a way that's worthwhile.

Personally, I would clean/bleach/scrub everything, put the tank back together, restart the nitrogen cycle by introducing some ammonia, and let the tank/cycle run while you're away. If you do that, you can leave the tank's lights off, but keep the filter on for water movement. You don't have to have a cartridge in the filter during that time, because the bacteria grow everywhere in the tank, especially the substrate, and will be fine without that one piece of floss or sponge if you don't have a new cartridge (I'd leave out any carbon for sure, in case it polishes the water too much and starves the bacteria colony enough to keep it from growing properly).

2. Do we really need the charcoal filter? I get that we need a bio filter for the good bacteria to grow on, but I'm a little confused about the carbon one. Basically we put it there bc it came with the kit. Other people seem to just use a sponge filter and rinse it every so often?

Some of that depends on the kind of fish. Goldfish are dirty, so they need a lot of filtration. Some other fish (like Bettas) don't produce anywhere near as much waste and breathe air through a kind of lung, so they're alright with much less filtration. Goldfish also like a lot of current compared to some other fish, so they like a lot of filtration for that reason, too. If you were to keep a bunch of plants and a Betta in this tank, for example, you might be fine with just a sponge filter (though personally, when I under-filtered my 5g betta tank with just a 3i Whisper I had to do small water changes every day or my fish was unhappy and the tank was nasty -- your mileage may also vary depending on how finicky both your fish and you are).

The carbon takes out organics in the water, which keeps the water clear and "sweet" (which is why people put it in terrariums and regular drinking water filters, too). That can be a problem if you want some kind of organics in the water (like tannins), but if you're not trying to add/keep organics it actually can make your life a lot easier (in terms of keeping down water changes and "pond" smells coming from the tank). You can use purigen as a replacement for activated carbon or in a mix with the carbon as your chemical filtration if you're not happy with the carbon alone. The advantage of purigen is that you can reuse it (after putting it through a bleaching, etc, process), but the disadvantage is that it binds to a different range of compounds than carbon does. In an ideal world, I'd use a mix. But since this isn't an ideal world (I'm too lazy to do the chores related to reusing the purigen and I use activated carbon for other/related things so I have it on hand), I just scoop some loose carbon into a filter sock and throw it in my HOB (along with a sponge and a plant growing in a DIY nylon bag).

3. How the hell do we keep ammonia down? We'd had the tank for a few months, so thought it had cycled fine and nothing seems to have precipitated the first spike and fish death. But I'd like to start off right. Am more than happy to monitor constantly to keep the fishie happy, but all of the questions I see online basically end with "big water changes". What if that just doesn't work? We tried to resort to an ammonia reducer a couple of times - which I know isn't a great option - and it didn't seem to work either. We tested our tap water and it came out with a zero reading, so it's not background.

Ammonia will spike whenever something is rotting. That could be food, or waste, or something that was going on with your goldfishes' bodies. You might not have been able to get the ammonia source out of the tank because it was in a hard to see/reach place (like in the gravel), or because the fish were just releasing an exceptional amount as they sickened/died. To a point, it might be a chicken-or-the-egg question, in that you don't know if the fishes' illnesses (or deaths) caused the ammonia spikes or the ammonia spikes caused the illnesses or if they fed into each other in a cycle. To me, this is the best reason to take apart your tank and start over.

Other techniques that people use to keep ammonia down:

-- Introduce fish/anything with a bioload to the tank slowly, so the bacteria colony has time to grow in response to the added ammonia load. For an animal with a big bioload, like a goldfish, that might mean just one goldfish and daily water changes and getting the tank re-settled before adding more.

-- Introduce plants and/or a "clean up crew" (like shrimp), which can carry some of the burden of keeping the tank clean. If you want to get goldfish again, you might introduce either really large/hardy plants (like Amazon Sword) and/or plant your HOB filter.

-- Added filtration, lots of smaller water changes, vacuuming the gravel. The vacuuming is especially important because if something is stuck in the gravel and you don't get it out, it'll just rot there and keep producing ammonia regardless of what other filtration/cleaning is going on.

4. How often do you scrub out the inside of the tank with an algae pad? I feel like maybe we weren't doing that enough.

Whenever you want. Algae looks terrible, but it's just a plant; it's not harmful to your fish. If you're getting a lot, though, it might mean your tank is too bright/hot (do you have it in direct sunlight?). Goldfish like relatively cold tanks, so that might have been stressing the fish. I doubt you cooked your goldfish and that had anything to do with their deaths, though.
posted by rue72 at 9:15 PM on February 11 [4 favorites]


Terrific response by rue up there, really terrific.

The only thing I would add is to maybe consider another hardy fish, that's not a gold fish. Guppies, white cloud minnows, all great, tough fish that have a sliver of the bio load that a gold fish does.
posted by smoke at 1:47 AM on February 12


Holy crap, thanks, rue72, that's great.

(Tank not in sunlight, don't think we cooked our fish either.)

Dumb question: when you say "Personally, I would clean/bleach/scrub everything, put the tank back together, restart the nitrogen cycle by introducing some ammonia, and let the tank/cycle run while you're away." what do you mean by introducing some ammonia? Actual, like, ammonia? Liquid? Or an ammonia source?
posted by gaspode at 1:58 PM on February 12


what do you mean by introducing some ammonia? Actual, like, ammonia? Liquid? Or an ammonia source?

You can use either actual ammonia or put in something that will eventually release ammonia (by rotting).

The old-fashioned method is to add fish food for a few days -- you can just sprinkle it in like you're feeding imaginary fish or crumble in that same amount to help break it down (slightly) faster. The downsides of the fish food method are: it can take a while to build up enough ammonia to trigger the cycle (to start with, the food has to start breaking down), it can be tough to know much food to add to get to the ammonia level you want, and there might be other things in your fish food that don't look great rotting in your tank (and could trigger algae growth, etc).

The more "high tech" method is to add pure ammonia until you get the tank water to +/- 4ppm (though you're probably OK anywhere from 2ppm to 5ppm). You can use ammonia from the cleaning aisle, just make certain that it's pure ammonia, and that it doesn't have any added fragrances/dyes/etc. There are calculators online to help you figure out how much ammonia to add, but you can also just drop in half a capful or so at a time until you hit 4ppm. If you go over 4ppm, do a partial water change to bring the ammonia level back down. Once you've got your ammonia level steady, that'll start your cycle, and then you're just waiting around until the ammonia starts dropping and nitrites start showing up so you can go on to the next steps.

Something you also might consider while you're starting the cycle: bacteria likes higher temperatures, so a heater (5W/gallon * 10 gallon = 50W heater) will probably speed the cycle up. If you go that route, you can keep it at +/- 85F during the cycle, then +/- 78F if you stock tropical fish (there are a lot of tropical fish and plants that do well in smaller tanks) or remove it/lower it further if you stock cold-water fish again (in that case, I second smoke's suggestion of white cloud minnows -- they're also related to carp and like the same cold/high movement/unplanted conditions that goldfish do, but WCM only grow to <2>
Anyway, I'm glad if this is helpful! Don't worry too much, I would bet that the issue with your fish was how they were bred and treated before they got to you; there's probably nothing wrong with your methods or equipment.
posted by rue72 at 5:23 PM on February 12


You can also but "fishless" cycling solution at aquarium shops of you don't feel confident. It will definitely work but it's a bit over priced if you ask me. It's often faster, but if you have time rues method is fine.
posted by smoke at 5:45 PM on February 12


Thanks! Tank is broken down and cleaned. Will start with the ammonia tomorrow. Awesome.
posted by gaspode at 8:33 PM on February 12


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