sorry bit confused your situation.Are you doing a fish in cycle using a filter from another tank that's only been going for 3 weeks?
If so, keep testing, keep doing daily water changes.Any time Ammonia or nitrite is above 0 do a water change big enough to get it back down.
The plastic bit that is broke is a brace (did you use it as a handle?) I believe they're there to stop the tank bowing, though i stand to be corrected.If they're not needed then why would there be one?
with the bogwood falling apart, if it's only small bits coming off. i wouldn't worry (you have just poured boiling water on it).If big chunks are coming away & it's distintegrating, i personally would leave it out.
Sorry about the confusion, I should have explained better! My old tank has been running for about 5 months but I'd been following manufacturer's advice and changing cartridges every 3 weeks. I then found this forum and stopped replacing cartridges. Last cartridge was changed about 2.5 weeks ago.
My new tank has an internal filter - I'll add full details to the first post on this thread soon - but as it hasn't been running, it won't have any bacteria in it. I was thinking of moving the media from the 21L to the new filter as an extra if I can fit it in - the models are incompatible so I can't simply replace the new media with the old one, the old media would have to fit within the new filter compartment. If I can't fit it in, I was planning on moving the whole old filter (as opposed to just the media) into the new tank whilst running the new filter. I assumed that although not fully cycled whatever bacteria may be present in the old filter, it could help the new tank cycling? I hope that makes sense. I don't intend to move the old filter and run it without the new filter as the old one wouldn't be powerful enough to treat the new tank, it'd be there just as an aid until the new tank is fully cycled.
Unfortunately my test kit hasn't arrived yet so I'll just have to keep doing daily water changes.
As for the brace (thank you for naming it for me!), yes I stupidly used it as a handle. I'd thought maybe it was there to support the filter and light that go on top? the joys of a silly beginner... I guess I'll have to replace it if possible then
I'll check the bogwood again.
Thank you for all the advice