Ummm...can you explain more what you mean by that?
Also, if I went with 1 1/2" bulkheads, would that force a minimum flow I'd have to keep up with?
[You can tell I'm new to all this
]
cheers
David
There is some engineering and math involved in planning a return system that will do the flow that you want...most simply throw stuff together, and never end up where they think they are. Static head, plus friction loss in the plumbing system (from the sump, through the pump, and up the return) = dynamic head, which is the number applied to the flow curve as head height.
Water in = water out. You cannot get more water out than you put in, so there is nothing you need to keep up with.
Unless you are pumping above 1500 gph, there is no reason in the world to use 1.5" bulkheads.
Ah, good to know - thanks!
I would like to eventually try my hand at SPS - what kind of turnover do I need for that? would 900 GPH be enough?
cheers
David
Well, the rules of thumb are arbitrary, and really do not hold any real value, since we cannot even think about approaching lateral or cross-reef flow in the ocean. What is important to realize and understand, is the relationship between recirculative flow (turnovers) and circulative flow (mixing/dispersion) is not supplementary or complementary (add to a "whole,") rather it is adjunctive. (related in a subordinate role.) Circulative flow, disperses the recirculative flow, to all points of the tank. Overemphazing the dispersion, at the expense of turnovers, simply keeps the "dirty" water in the tank, rather than supplying "clean" water to all points of the tank.
You have to view an aqaurium as a living thing. It has a heart, blood vessels, kidneys, liver, etc. (some even have brains.
) Think of it like this: If the heart does not put out a sufficient volume, you can expect poor health, and very possibly death.
The difference with an aquarium is the heart pumps, however, there are not blood vessels in the tank, to move the water where it needs to go. An adjunctive aid is needed to keep the blood "flowing," because the return is not able to disperse the water (despite the silly gadgets intended for this purpose, and multiple outlets.) In days past this was not a concern as water entered the top, and exited through the bottom or vice versa. Hence power heads were put into service. The flow rates back then were due to misunderstanding as well.
The systems always did better at higher flow rates. They were not single pass sytems, and still aren't. I first realized this back in the early 80's. Was running an 80 gal, with a March AC-3-MD, through a UG. (rated around 750 gph, probably actually putting out around 400 gph.) After fighting with the tank for quite some time, and some odiferous emissions, I swapped the pump out for a Little Giant TE-5MD-HC, rated ~ 1200 gph, ( Current price check only: $400 on ebay, SRP is ~ $800, and it still runs) and the problem cleared up, and never had a lick of trouble with the tank after that...
So how many turnovers do you need? Higher is better, (volume,) but remember the power heads are adjunctive aids, not the whole show, as many would think. You need sufficient circulation in the tank to prevent "dead spots;" the rest is basically nonsense. Higher flow in the tank is not at all a bad thing, however, since it is adjunctive, you oughta be upping the return flow as well.
This is a fairly hot topic, and it is often way overthought, or way under thought; even makes for some lively debates, which is not all that great. However, the model for an aquarium is a living organism, not power usage, or rules of thumb, or even common practice.