[somewhatshocked]

water changes every couple of weeks

No need to do water changes while undergoing a fishless cycle.

Even with the Nitrifying bacteria being only ~10% efficient (as per some sources) at 6-6.1PH

I routinely cycle tanks with much lower pH and temperatures in the 60s Fahrenheit. So 6 should be fine.

I feel like I should be seeing some nitrites in my water by now.

Your tank may already have had a nitrite spike. It could have happened in a matter of hours such that you would not have been able to detect it if you were testing every day. If that's the case, you'll know your tank is 'cycled' once it can process a fixed concentration of ammonia (3PPM, for example) within a 24 hour period with no detectible nitrite.

Edit: And if anyone happens to recognize the buildup on my silicone, I'd love to know what it is! It looks like bacterial colonies to me, but it is unsightly.

Not specifically sure what it's called but it's a normal growth with new tanks. Nothing at all to worry about it.

 

[somewhatshocked]

I will stop any water changes in an attempt to edge the PH upwards as per your advice on the matter.

Definitely don't try to chase pH. Just let it rest where it will be once the tank is cycled.

When you cycle at low PH and low temp how long does it usually take for you?

Usually about 4-6 weeks, circumstances depending. I usually cycle with substrates that release a ton more ammonia and my water is always in the low 60s if I can help it. pH from ADA Aqua Soil Amazonia is sometimes around 4.9/5. kH 0, gH 5-6. It's sometimes taken 8-10 weeks or longer but that's only been on a few occasions.

Since you have warmer temperatures and much less acidic (10x less at least) conditions, your tank should probably be done in another month or so. I would expect that you may not see a nitrite spike, though, and may want to focus on watching ammonia get consumed and eventually nitrates rising. I've gone through the initial 'cycle' without ever seeing a nitrite spike so many times I've lost count. But it's never not frustrating when it happens - even if I expect not to see one for whatever reason.

It's incredibly tough for me not to get impatient but it has always paid off in the end. Allows time for plants to grow in, the tank to mature and everything to look great before any livestock gets moved in.