Fishless cycling a blackwater tank. Combo fishless/silent cycling?

[Seisage]

I have some questions regarding cycling a tank characterized by a lot of tannins and low KH and pH.

I’m working on setting up a biotope tank with these conditions. I’ve read through the fishless cycle guide here on the forums and I’m pretty familiar with the nitrogen cycle as a scientific concept. However, in reading the guide, I see that pH below 7.0 can notably delay the cycling process. Of course, that is at odds with the biotope I’m going for. What would be the best practice for cycling a low pH tank? Should I establish the cycle and then add the wood and leaf litter? Seems counterintuitive and I suspect a change like that would throw things off.

The tank will be planted, but not extremely heavily. I’ll only have floaters (frogbit and water lettuce) and while they’re fast-growing, there’s only so much volume they can attain before running out of surface area. So, while I could try a silent cycle, I’m not sure I’d have enough plant biomass for it. Plus, it’d be great if I could add a full tetra school at once instead of having to wait a week or two between additions of 3 fish at a time.

Would a combo of the fishless/silent methods work out? Maybe follow the fishless method, but dose lower ammonia as to not damage the plants?

Other relevant information:
-Tap water pH: 7.2
-Tank pH with tannins is unknown (holiday traveling has halted tank setup). Probably shooting for somewhere between 6.5-6.8. Exact GH and KH currently unknown for same reason, but hardness in my area is around 20ppm
-I do have an established 5.5gal I just adopted from someone. I could transfer some of the substrate to seed the new tank, but I don’t have a ton to work with, plus it’s got a lot of detritus and detritus worms (maybe that’s a good thing?) Can’t transfer filter media. It’s one of those cheap little internal filters with replaceable filter cartridges. Maybe I could replace the cartridge and put the old one in the new tank?

 

[Naughts]

You are probably correct in concluding you don't have enough plants to silent cycle. It takes a lot.
Rather than ammonia, which can damage plants, I would use the old filter cartridge and the substrate from the small tank. A gentle rinse with dechlorinated water should get rid of a lot of the debris without harming beneficial bacteria.

 

[Seisage]

You are probably correct in concluding you don't have enough plants to silent cycle. It takes a lot.
Rather than ammonia, which can damage plants, I would use the old filter cartridge and the substrate from the small tank. A gentle rinse with dechlorinated water should get rid of a lot of the debris without harming beneficial bacteria.

Perfect. Should I try to use all of the substrate from the small tank? It is planted, so I don’t think I’d feel comfortable taking it all. The new tank is also 25gal, so quite a bit larger. Would a couple handfuls of the old substrate be sufficient?

Regarding tracking the cycle, if I don’t add ammonia myself, what would a good testing schedule look like? Every few days like the fishless cycle method or just wait until I see significant plant growth and then test and follow up with an ammonia challenge? Would I still have to follow the 1-3 fish at a time guidance for the silent cycle?

 

[Naughts]

Would a couple handfuls of the old substrate be sufficient?

Yes, along with the filter cartridge.

what would a good testing schedule look like? Every few days like the fishless cycle method or just wait until I see significant plant growth and then test

Wait two weeks and ensure the plants are growing (photos help spot growth). Then add the cartridge, substrate and a few fish and test. Do a large water change if ammonia or nitrite show. Not 1-3 but a species group so they settle quickly which is less stress for them. So if you were going to stock 10 cories, 10 rasbora and 10 pencil fish; you add a species group of 10, monitor for a week or two, then add the next group of 10 etc. ( You should consider quarantine wherever possible).
Don't bother with ammonia as the fish provide that.

When I have done this I see nitrite once fish go in so I do 1 or 2 water changes but the tank then cycles within a few days.

 

[Colin_T]

low KH can stall the cycling process due to the filter bacteria using small amounts of carbonates to grow.

 

[GaryE]

I've noted before I don't cycle tanks with ammonia etc, because I have very soft water and filters I can move from tank to tank to spread what bacterial wealth I need.

I am curious though, as a no test kit aquarist. Since my issue is far less toxic ammonium and I do weekly water changes to keep my fish healthy - how does the fishless cycling concept affect those of us with soft, acid water? Ammonia versus ammonium?