Tank Cycling

Tank Cycling

Hello Venus,

I’m goldfish sitting again. This time, just for 12 days. Since the pump and pond sponge was added last time, it appears that good bacteria were able to grow in the tank!

This is a 5.5 gallon tank with 3 small fantails. Unfortunately, I will not be able to upgrade the tank size as it is not my tank 🙁

Current readings are:
Ammonia=0, Nitrite=0.5, Nitrate=5, pH=7, KH=0.
(No GH reading until new tester arrives).

One of the fantails’ tail frayed before and apparently the tank was salted. When the tail healed, it became black. Current salinity is 0.03ppm. One side of the black tail is longer than the other. I’m not sure if it’s completely healed but I imagine this happened as a result of cycling. The top fin of that fish is also slightly torn. Should we add any treatment to assist in the fin/tail healing? Or is fixing water parameters enough?

Do you think we are in the middle or tail end of cycling this tank? With the current nitrite and nitrate levels, how often should I be doing water changes and how much water should I be changing? Should I dose Prime for the amount of new water added or the entire 5 gallon tank?

Since the KH=0 (very low mineral quality), should I add some backing soda? Our tap water also has close to no minerals and low pH. I have already ordered some small wonder shells to arrive next week. In the meantime, should I add baking soda to raise KH and then add the shells to maintain KH? Or just wait for the shells and rely completely on the shells to raise and maintain KH/GH? If I add baking soda first, how much should I add for 5 gallons?


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  1. emme April 14, 2018 at 3:15 pm

    Hi Venus,
    I think the maximum time the fish will be in transport should be 1hour, likely less. My concern now is the Nitrate in the tank water used to transport them. You know I’m scarred from the last time. Will shallow tank water with Nitrate harm the fish? I noticed ammonia =0.1, Nitrite=0, Nitrate =10-20 so I’m cutting down on feeding and did another water change dosed with a full dose of Prime for the tank

    • Venus April 15, 2018 at 6:06 am

      These are real concerns, as fish that have suffered nitrate poisoning have no tolerance of shallow water. I wouldn’t cut down feeding, because your brother will feed normally, and this could cause a spike. Yes, the Prime will be helpful, as it will convert 10 ppm of nitrates per dose, or so they say. I would chill their tank water before the move, and this will doubly assure they feel no pain; 50 to 55f if possible. This way, if they were to have car trouble, it buys time. If you move them in an ice chest, the water stays cold for a few hours

      It will be hard to say goodbye?

  2. emme April 8, 2018 at 8:04 pm

    Hi Venus,
    Ammonia =0-0.1, Nitrite=0 and nitrate=5-10.
    KH=110, GH=160.

    I think it’s safe to say that the cycle is now complete?
    I am preparing to return the fish tank in the upcoming week.
    Now that the cycle is complete, how often should water changes be done? And how much water should be changed out? I am slowly transitioning back to feeding just flakes twice daily.

    When it comes to returning the fish, I had in mind to remove half of the tank water into a bucket and place the 2 fish into that bucket for transport. Then leaving the other half of the tank water in the tank with pump immersed for transport. When everything arrives at my brother’s girlfriend’s home, should they just fill the tank with treated fresh water? Or add the bucket water back in?
    What’s the best way to transport? Thanks!

    • Venus April 9, 2018 at 7:33 am

      How far will the fish have to travel? If an hour or less, a bucket is fine, but if the distance takes more than an hour, chill the tank water so they’ll use less oxygen. In this case I use an ice chest which keeps the water colder for longer

      Witht they cycle being so delicate, it would be wise to keep as much tank water as possible. If you can keep from adding more than 15% of freshwater that would be good

      Yes, I think the cycle is complete, but still delicate

      If you could transition your water changes to match the water changes you know they’ll perform, that would be great. If they’re willing to increase the number of water changes, instruct them on how you’ve been doing things. No matter, all changes in maintenance routine should be done very slowly. It all pertains, how much freshwater is added, how much waste water is removed and how much food is fed. Any change can result in a spike; nerve wracking isn’t it? A well established cycle can take a lot more than a new one

  3. Venus April 2, 2018 at 5:40 am

    Yes, you can slow the water changes as the parameters improve. For example; if one day you have a reading of .5 ammonia, and you perform a water change using Prime, assume the ammonia is converted with a half dose of Prime. If the reading is the same the next day, there’s no reason to do a water change. On the other hand if the levels have increased next day, you would need to do water change and add appropriate amount of Prime

    If you know ammonia is rising though, increase amount of Prime to be on the safe side, but this probably isn’t the case

  4. emme April 2, 2018 at 12:42 am

    Hi Venus,

    Just an update on the tank cycling. I’m feeding twice daily (peas in the evening, flakes in the morning).
    Ammonia =0.1, nitrite=0.1, nitrate=5, KH=100, GH=180.
    Still doing water changes of 15%. I’ve reduced Prime dose to cover just the amount of water I’m adding because the parameters seem ok. Since the water parameters are consistently low, can I switch to water changes every other day? Perhaps the good bugs will grow faster this way?

  5. Venus March 12, 2018 at 4:57 pm

    I emailed you, and yes, I regret not moving it to the tub, but SSG can result in the very same symptoms, and the fish would surely die if these gases were present, so you did the right thing. I’ve seen fish in the curled position for several weeks before treatment was offered that recovered. Every fish and every situation is different

    When a fish curls, it does so because the blood is thickening, and the body is constricting. It must be very painful. The fish should get relief in the deep water

    Should also warn you, once you add the Mean Green, you’ll need a flashlight to see the fish. You should be able to view it by pointing the flashlight on the side of the exgterior wall of the container

  6. emme March 12, 2018 at 3:40 pm

    So, the worst happened and the black-tail fish succumbed to nitrate poisoning.
    I found its body curled against the pump sponge today in the tank. I regret waiting last night and no taking it out of the tank sooner. I’m not sure how long it will survive now? It looked like it was having difficulty staying conscious and when it tried to move, its body was thrown with the water current from the pump and pushed toward items in the tank.
    I scooped the fish out of the tank and placed it into the deep chamber (20 gallons; 24″ deep) of water pre-treated with remedy from yesterday night. I also re-dosed with enough Prime for the whole 20gallons and hydrogen peroxide before placing the fish in. Before I left for work today, I noticed that the fish sank to the bottom of the chamber in its curled position but because it was too weak, its body also followed the water current and was pushed up and down in the chamber. Seeing the fish’s condition, I’m not too hopeful it will last more than a few days? How should I continue to treat this chamber tonight? Should I continue daily water changes? How much water should I change out/ replace?

  7. Venus March 9, 2018 at 8:10 pm

    Consistency in water changes, sponge rinsing and feeding are the things that matter. If you’re going to change something, do so very gradually

  8. Venus March 9, 2018 at 8:07 pm

    Are they all laying on the bottom, or just hovering above it, which is normal. Fish rest most of the night, and parts of the day. The older the fish, the more it rests.

    Okay. We might prepare for a spike after you increase feeding (slightly) and back off on water changes. I sell established pond pumps now and then. When I pull one from my tank, I feed a lot less, gradually working my way up. I’ve developed a feel for it, and never get a spike due to the fact. I think we all have this ability to feel our way through things, and although some parts of fish keeping are mater of fact; some aren’t

    If you damage the cycle? How will you know? There will be an ammonia or nitrite spike. As long as you’re getting zero for ammonia and nitrite with a healthy consistent reading of nitrates, the cycle is in tact

  9. emme March 9, 2018 at 1:17 pm

    Ok, I’ll back off on the h202 and water changes for now. I’ll feed small amounts of flakes again, yes. Though I really only started peas 2 days ago.
    I’ve used h202 for around 3days now. If I stop using it tonight and tomorrow and start your remedies on Sunday, will that be too much h202?
    I’m noticing that all 3 fish kind of bottom-sit/linger where the black-tail fish is in the morning. Is it because I am doing a lot of water changes? Hopefully I didn’t kill the cycle…

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