spear like plant at the front
Sold to me a long time ago as a variety of cryptocoryne wendtii, I grew a load a few years back in a propagator in garden compost, kept moist at the roots with good air humidity and fairly well lit with a strip light - but the name covers a range of fairly variable looking plants, leaves come, less and more crinkled, and some are very brown specimens, some very green. Hard water tolerant so may prove a plant you could have easy success with, they do however, like a bit of nutrition in the substrate.
I also grow balanasae but it seems to really need a really rich substrate at its feet and more light than most crypts. My pick for ease in hard water if you want to focus on crypts is ciliata, which copes really well in hard water, not easy to find however.
CO2, but struggled to find bottles
I gave up years ago on refilling, bother and pricing, I now use a refurbished fire extinguisher - Amazon - but I find 5 Kg bottles a bit intimidating, though it lasts a year, and in the past have had more than acceptable lower maintenance tanks using a range of slow growing plants and no CO2 and soil under fine gravel and sand. Though generally if water is harder and plants are capable of biogenic decalcification for CO2 they require more light energy for this process. And of course, the process changes the pH of the water, sometimes quite significantly over a period of time and produces deposits.
If I was redoing my tank, which I may do, I would go for more soil - in bags to stop making a mess when pulling things out, I have used mesh bags filled with pond compost in the past - an up-market yeast & sugar CO2 system and somewhat less light, maybe around 100 watts of high lumen output LEDS, well spread. And no external filter, just two cheap large hang-on the backs without trickle facilities. I find externals such a bother - age I fear, I hate disconnecting them and lugging them about and I have had leaks in the past, from a 'top of the range' brand.
Anyway, the moral of all this is, that with the right balance of light, nutrition and plants, you don't have to have CO2 injection and, you certainly don't have to go for high pressure cylinder CO2.
I am a great fan of floating plants, yes they need thinned regularly, maybe once a week if light isn't strong, but they are excellent indicators of nutrition issues and they really help keep the water sweet and reduce algae issues. Hornwort loves hard water, my favourite Amazon frogbit is I have found not too keen on very hard water so you might not succeed with it.
Keep us informed here what you decide to and do continue to provide the odd photograph, rest assured folks here are genuinely interested in other folks projects and want to both help others and learn from others. After nearly 60 years in the hobby I learn something new here most weeks!
