Hi a have a rio 400 tank which has a variety of tropical fish in the main ones bein silver dollars silver sharks , torpedo barb and parrot fish. The tank is currently decorated with just ocean rock. i have planted it out before and it looks amazing with plants but despite giving liquid fertiliser they eventually die off or get destroyed by my fish! im guessing silver dollars. the lighting i have is the standard juwel t5 tubes.. basically what im asking is is it worth investing in co2?? will this help my plants grow at such a rate that my fish cant eat them quick enough to destroy them? any replies appreciated thanks