Help - who's right here? Pet of the Month
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Fish Fanatic
Apr 28, 2020
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Dorset, UK
Yesterday I cleaned both my tanks (180l and 130l) including the filters. Afterwards I omitted to reconnect the main filter on the smaller tank, and also the heater. Both were off for just less than 24 hours. I keep a small emergency filter running in that tank (ready for the hospital tank when needed and also for its spray-bar for oxygenation), but its capacity is around 30l and that ran throughout the 24 hour period. By the time I realised what had happened, the temp was down to 21degC but the fish (Platys and Black Widow Tetra and Corys) seemed none the worse and the temp has now risen slowly back to normal. My husband said none of this was a big deal - but I'm a worrier.
I tested the ammonia and nitrite and it was fine at that point (this tank is not overpopulated) but I was concerned about the main filter having lain idle in the tank for 24 hours and since we're going to be away a couple of days and I won't be able to monitor whether the cycle is crashing or not, I decided to swap that filter for another spare I always keep running in the other tank, just in case. My husband took the view this wasn't necessary, but as I said, I'm a worrier so .... Anyway, in the process of removing it, I managed to snap the hinging bracket on the suspect filter, but it's still operational.
Here's the marital strife bit. "Great," said my husband, "now the filter... that didn't need swapping in the first place ... is broken."
Cue Armageddon.
Who's right here?
Is that because the 30l filter was working? Or because you can just leave a tank idle for 24 hours without ill effect, in which case I'm wondering why he bought a 12v battery and an invertor for use with the tanks during power cuts.
I don't know the exact science where nitrifying bacteria is concerned, 24 hours is a long time and most would have died off by then I'd imagine...but I'm assuming your tank is established and that there's plenty of good bacteria living in the gravel etc for you not to have to panic about a crash. I've had an empty tank sit with just a few inches of water to cover the gravel for the best part of a week and still had a cycled tank by the following week when I set it up again 🤷🏻‍♀️
Does the tank have live plants?

After a water change I noticed the internal filter had slipped and was at 45 deg. To avoid getting wet I turned the filter off, repositioned it, washed my hands and forgot to turn it back on. A week later I went to turn the filter off for the next water change and realised it was already off. Panic time, out came the test kit to reveal zero ammonia and zero nitrite after a week with no filter switched on. The normal behaviour of the fish should have told me the same. I do have live plants including floating plants, but as CaptainBarnicles said, there are bacteria on every surface in the tank.
That's very reassuring. I have only a token live plant in each tank - I'm not very successful with them. But I might consider trying again if that is a factor in preserving the status quo. We've had some longish power cuts recently, like 7 or 8 hours, and after waiting for a couple of hours I've connected the invertor/battery set up. Looks like I don't need to do that then.
Wonder if my husband is right about me not needing to rigorously carry out a weekly min 30% water change and a five weekly filter clean too?. :p
Keep doing your water changes on a weekly basis, with no live plants I would suggest bigger than 30% to remove as much Nitrates as you can. Filter maintenance....meh, I'm pretty slack with that but once every couple of months sounds about right
If a man speaks and there is no woman to hear him is he still wrong ?
I believe there's a rule against throwing fellow forum members into existential crises. I'll have to look it up...

OP, if in doubt test ammonia and nitrite for a few days to make sure your filter is still cycled. I recommend keeping up with weekly water changes and rinsing out the filter media approximately whenever you get around to it. The exact frequency depends on the fish and the stocking level.
I wouldn’t worry to much about it. If all your fish seem good you should be good. I never change the water in my tank I just top off the water when it gets low although I probably should do water changes. Unless the fish start gulping for air at the top of the tank their water should be well enough oxygenated and it takes a while for the ammonia to raise if you have good bacteria.
Thanks everyone for your insights. I shan't mention this to my husband. :( I still want to know why he bought the invertor/battery but I'll leave that discussion until things have settled down.

I did the same recently - accidentally knocked a rocker switch off so the filter and integrated heater were off for 24 hrs. The temperature dropped significantly but the fish all seemed OK. I turned everything back on and monitored the water for a couple of hours - everything was fine.
On the other hand, some years ago a pump failed on a marine tank. I was concerned about turning it straight back on so I removed the fish to a large bucket. Good job I did because there was an ammonia spike and the water smelt awful when I fixed the pump.
I went to work leaving the fish in the bucket thinking I would need to set up a temporary tank later, but when I got home the tank was back to normal so they went back in, none the worse.

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