Welcome to TPT!
Did you cycle the ADA substrate before adding fish? This stuff throws off TONS of ammonia for about the first 4-8 weeks, so you need to get your water tested ASAP.
I suspect that this may be the underlying source of your algae issues.
Also, DIY CO2 may not cut it for a tank this size- VERY difficult to obtain and maintain the consistent levels you need.
Thank you for your reply! I'll keep this in mind and might switch to pressurized one day.
This tank has already been in cycle for 1-2 months. Just no luck in plant growth.