Cycle status unknown, testing mid cycle.

[Danbruski]

Hello all. Great forum. Learning lots.

I’ll get right to my question, and add background after.

1. How do I know if my tank is cycling?
2. If it is cycling well, do I proceed in adding a couple fish at a time and check the cycle before adding more?
3. If it’s not cycling completely yet, what steps are left?
   
   
   25 yr old tank, empty for the past 20 years.
   Started up in Sept 2020 for the kids
   TopFin power filter, removed cartridge and replaced with sponge, bio balls, polyfill, old cartridge floss this week.
   V1: Guppies, Cory cat, Otocinclus, 2 plants
   V2: platy, Cory, neon tetras, snails, 2 plants
   Most have died. About 15 fish since Sept. Never more than 7 in a tank at once.
   I didn’t know much about cycling before adding fish. Trying to do cycle with fish. I’ve only now received a proper test kit, so I dont know my numbers from before this week. Other mistakes like heavy gravel vac was done. We used starter bacteria (who knows it anything is alive) and Prime. Weekly 25% water changes.
   
   Yesterday:
   Ammonia 0
   N02: 0
   N03: 0
   pH: 8
   
   Today:
   Ammonia 0
   N02: 0
   N03: ~5, but then I look a few moments later (6min of rest) and maybe 10?

 

[Aiken Drum]

Test daily. Your target should be to keep ammonia + nitrite combined below 0.5ppm. Do whatever water changes you need to maintain those safeish water parameters. If it gets to 0.5ppm do 25% water change, if you see it creep up to 1.0ppm combined do 50% water change or a couple of 30% changes a few hours apart. When you are consistently seeing 0ppm ammonia and nitrite and your nitrate is rising your cycle should be sufficiently established to support your current stocking and you can safely add a little more bioload (like another 30%). Rinse and repeat until fully stocked.

 

[Aiken Drum]

Another thing i noticed was your otos. Im not too sure if the fish you mention are still alive or are ones that you lost during your initial set up.

Otos need a well established tank as they feed on algae and biofilm that come with time. They arent suitable for a new tank and could starve.

 

[Danbruski]

Thank you Aiken for the reply. I’ll keep testing. That’s one positive for working from home during COVID - lots of opportunity to test.
When we did our first test, I was really surprised to not see high Ammonia, especially with the death we’ve had. Low to no Ammonia and 0 Nitrates and Nitrates yesterday seemed odd. At least I think I’m seeing more Nitrate today.

 

[Aiken Drum]

If you have had fish in the tank since September 2020 (even though they died) you should have a fairly well established cycle now and your parameters support this. Ammonia tends to take a while to manifest into deaths, so this would explain fish dying in what are now good water parameters.

It used to be a fairly common practice to throw some feeder goldfish in a tank to cycle it. When they die, replace them, when they stop dying you are cycled and you replace them with what you intend to keep. I still hear of people doing this occasionally.

 

[Danbruski]

Ok. That’s good to hear - about my cycle and stretched out fish deaths. We also had some guppy guppy aggression and nipping with the first batches. We’d find a dead guppy with its tail chewed up.

So just keep watching, change some water when nitrates are up, and start increasing fish #s?

I’ve heard to increase only 2 at a time or so, but we also heard a small number of community fish can stress them because they are used to a group. We are shooting for guppies, Cory, maybe tetras.

 

[Aiken Drum]

As said, while cycling, do water changes sufficient to keep ammonia + nitrite combined below 0.5ppm. I really think you arent going to see those numbers unless you do something like put a lot of extra fish in at once and your cycle will then need to catch up.

Once cycled, water changes to keep nitrate below 40ppm is typical. If you need to change more than 50% weekly to achieve this you are overstocked. If you arent getting high nitrate even without water changes i would do a small (25%) water change every couple of weeks.

With regards to increasing numbers, 30% increases shouldn't put too much pressure on your cycle and it will catch up quite quickly. So if you have 6 fish, add another 2. You can add more, but it will take longer for the cycle to catch up and you should look out for ammonia/nitrite spikes and do water changes if required.