Am i good to go? Unsure whether tank is fully cycled...

[Jmurray17]

Hi everyone,

I have inherited a 4ft (75 G) tank and I think I have been cycling successfully for about 8 weeks.

Heater set at 26 degrees centigrade.
Gravel substrate.
Live rock
2 T5 lights
1200 LPH canister filter 30W with filter media from my established 50 litre tank.


I also inherited a very old test kit and have been using that.

Have been checking ammonia and nitrites daily and dozing amm up to 4ppm with food flakes.


The last week I have had stable readings of
amm =0 ppm
Nitrite =0 ppm

I added a small school of 3 tetras into the big tank 5 days ago.
They don't seem stressed, breathing normal rates, swimming well and feeding as usual.


First question...am I cycled as I have a ghost knife I need to rehome into the new tank but don't want to risk putting him in too early?
Second question....do I need to put the tetras back in my established tank if there is any doubt about my large tank being cycled?

Third question is....as I am using an old test kit (I mean like 5-6 years old) it doesn't test for nitrates? If my ammonia and nitrite readings are within safe parameters am I able to assume nitrates are being produced?

Also I have not done a full water change during my cycle only topping up what has evaporated, have dosed the water with ager each time I have added water.

Thanks in advance!



Edit: stupid question but do I want nitrates or are they supposed to be 0ppm as well??

 

[tarpon]

Nitrates are the end result of the process. The end goal of a cycle would be 0 amm 0 trite and any number of trates. Nitrates continually build up, and this is the reason we do water changes, to remove them.

If you had an ammonia and nitrite spike during the cycle, and they both reach 0 within 24 hours of dosing ammonia, then I'd say it's finished.
BUT, I wouldn't trust the old kit. If you go out and buy a fresh, liquid test kit, and everything checks out with 0 amm 0 trite and however many trAtes, then I'd go ahead and add more fish.

 

[librarygirl]

So you've had the nitrite spike and then fall, yes?

If so then you're probably cycled but a nitrate test would confirm. Nitrates may have built up pretty high during the cycle, so I'd do a couple of 50% water changes just to be on the safer side. A nitrate test would be helpful.

What kind of test kit are you using? 5-6 years is pretty old and I wouldn't trust it. I think the API ammonia and nitrate tests last about 3 years and nitrite about 4, so I would definitely get a new kit.

Are you using dechlorinator or just aging the water? Is it tap water? Using a dechlorinator is a good idea and a lot easier than aging water; plus if your municipality uses chlorine then it'll gass off, but if it uses chloramines it won't. It's easier to just dechlorinate the water before using it (Prime is one of the best ones).

Also, yes you want nitrates; they are the end product of the cycle (ammonia converts to nitrite which then converts to nitrate). In a cycled tank you'll always have some nitrate (the amount will vary depending on fish load, how much you feed etc). Keeping them below 20 is generally good practice though.