It grew like a weed in mine, I was using ADA Amazonia soil and dosing EI (on the light side looking back). Started off as a CO2 tank @2bps but the pic below was after 3 months with no co2 which I was surprised about
Big trim on the C. Helferi, due to emerged growth dying back, missed one though...
Added half a dozen snails, loads of food for them on the wood plus the glass, which I didn’t clean this time. Let’s see how they get on.
Are the plants still potted to stop the goldfish digging them up? If they are then they will do much better planted with some root tabs under them. It can be hard for them to spread out of the rock wool.
It's a bit of a cliché but hornwort is a great plant for coldwater aquariums as it happily floats making it impossible for the goldfish to dig up. Elodea is another one that does the same as is water sprite. I like paraguay's hygrophila suggestion as well.
I’ve added a few floating bunches of Elodea and Hornwort for now and will try planting the potted plants with root tabs at the next water change. I originally kept them potted so I could remove them and clean around them more easily. Happy to give anything a try
I might add some Hygrophila at the back if the fish leave the other plants alone - so far so good!
I changed my mind about planting the C. Helferi in the gravel. Keeping this tank clean is going to rely on me being able to remove the hard scape in one piece and I don’t fancy trying to negotiate two fish and plants when I return it to the tank each time. Don’t worry though, the plants haven’t gone to waste, they’ve found a new home in my other tank.
Water change done, damaged leaves removed and diatoms cleaned off manually. Really wish I could find a way to get rid of them completely maybe the lighting tweaks will help. Dosed 15ml of TNC with a little extra Seachem Iron after reading a post on here somewhere that suggested the iron in TNC complete isn’t very effective in hard water. This was mainly due to the most recent leaf being much paler in colour to the others, which I understand can be a sign of low iron.