[pc604]

Hi everyone,

What are your opinions regarding HOB refugiums as a means of nutrient control/export (particularly phosphates & nitrates)?

Are HOB filters generally too small to be effective? I've read that refugiums should be at least 20% of the main display, and also that a 10x-20x flow rate is generally better for macroalgae growth and prevention of buildup of excess particulates/detritus that may promote nuisance algae growth.

So here's what I think, and please correct me if I'm wrong:

There's not enough room in most HOB filters for a healthy amount of macroalgae. That being said, HOB fuges are pointless for big tanks but may be somewhat effective for smaller tanks (20 gallons or less). Also, if you do manage to stuff the HOB compartments full of macroalgae, that cuts down on the flow considerably resulting in mass buildup of oils and detritus. Now I'm not doubting all the HOB fuge users on this board as I know many of you have had great macroalgae growth in your HOBs, but I'm just curious about the before and after results as I have a 20 gallon nano myself.

Did you notice a drop in nitrates and phosphates after a HOB fuge was applied? What size tank was it applied to? If you did notice a drop in nitrate and phosphate levels, was it a result of the installation of the HOB fuge or did it result from a change in your reef husbandry routine? I bring this up because I think when most aquarists discover they have high levels of nitrates & phosphates and are considering building or purchasing equipment to help correct the problem (eg. refugium, phosban reactor...etc.), he or she will also start to change the way they do maintenance (eg. large and frequent water changes, feeding less ... etc).

Thanks!