Originally Posted by theblondskeleton
I'd recommend juvies at least 4". They still have some growing to do but not so much that it could do a lot of damage with less than perfect water. You could certainly go from there with this plan.
Sounds like you have given this some thought! Typical BB rearing utilizes sponge filters for the bacteria colonization (similar to the pumice blocks you propose) so i imagine the theory behind massive daily (i never did this) water changes is dissolved organic solids. Not sure about the hormones... Sounds like metascience to me.
Thanks, 4" juveniles are still quite decently priced so that wouldn't be a problem. Some thought given to this subject, but not an enormous amount. Just began researching this during the weekend basically, but the internet is quite a vast trove of information, as well as a vast backwater of hokum if you don't look very carefully!
The most informed looking opinion I've been able to find on growth limiting/inhibiting hormones (GIS) thus far is that they do actually exist though not at all in the manner that most people believe, and can be mediated by: carbon or zeolite filtering, protein skimmers with or without ozone, water changes, and with the use of live plants
and live rock. So I could in that case cover four out of five easily! Nitrates are also described as a growth limiting factor, but those can certainly be dealt with in better ways than water changes.
The pumice and other denitrators supposedly actually support (beneficial) anaerobic bacteria colonies deep within them, unlike sponge filters. The idea is that the medium has tiny pores which only let water trickle through slowly enough that the oxygen is stripped by the outer aerobic bacteria thereby allowing the anaerobic bacteria to survive and thrive. And the anaerobic bacteria are the only bacteria that are able to break down nitrates into nitrogen, but they need an absence of oxygen to survive. Simple solution, eh?
Apart from the aforementioned parameters, I'm still not sure what Dissolved Organic Compounds (DOC) are, or why they'd be detrimental. I note that Tom Barr suggests in another thread that activated carbon will take care of these if you need to.
So if the GIS compounds such as "ammonia salts" are taken care of by usual aquarist practices such as using activated carbon, and keeping plants, if ammonia/nitrites/nitrates are kept in check with plants and appropriate filtration, and if activated carbon is used weekly to remove whatever other D.O.C. people speak of then is there still any reason to do water changes people?