Hey clm08kI also agree with twentyleagues and what magpie was saying with all their comments and the 75% WC 1x a week.
In my 55g with AC 110: I have
2 mokes 9-10in
1 polli 9-10in
1 del 9-10in
1 albino sen 6.5 "
3 giant danios
3 congo tetras.
I have to do 75% WC every 3-4 days because of high nitrates. I also feed every other day. So if you doubled the volume, it would make sense that you would have about a once a week water change. I don't know if 90g is suitable for life, but it definitely will make a great home for several years! Originally I wanted a 90g, but after having my group for more than a year, now I'm starting to think I need a 120 or 125. The problem with polys is that you will want more. hehe! Welcome to the forum!
Thanks for you input, I think knowing this then the 75% WC 1x weekly should work out for my 90g. And well the issue just is that I can't go any bigger than a 450L (120g I think?) due to floor weight restrictions. The 450L will be spot on the limit of what i was told that I could get, more weight could potentially harm the floorheating and that's not really what I want to do So I have that option still open and would go for this one and maybe just fill it to like 75% to reduce the weight a little. I think this should be enough to house them a lifetime
I'll see what future brings, next goal is to clean my aquarium tomorrow, rescaping it and then getting the senegals that are at my lfs probably mid next week. Ordered the rest already and I should get the other polys earliest next thursday so everything should work out nicely.