What temp is your tank? Warmer tanks make for faster growth. The new growth initially is lighter, but darkens over time. I see this most on magenta snails.
And that would probably explain it. The temp is at about the top of the green level on every thermometer I have, which I think is 80 degrees, even though I set the heaters for 77 degrees.
Would I be better off scaling back the temps a little bit over the next couple of months?
temp fluctuations cause growth rings. In an ideal world, the temp would be lower. The higher temps increase growth rate, which makes the shells thinner and also shortens their life span. I prefer mid-70's, that being said, they do well at your temp as well just live slightly short time.
What if I gradually cut the temp back about a 1/2 degree every two weeks. That should get me to where I need to be in 4 to 8 months. What do you think? I might also have to buy a chiller for the tank in the summer.
i find that if you drop the water level a little it helps keeps temps a little cooler as well from increased surface agitation. The growth ring you would see would not be significant. Bridgesii only have a 12-18 month typical life span. I think a more significant growth ring would be better than spreading it out to avoid it.