[mr.wilson]

Originally Posted by sphelps

External skimmers can make a big mess which is why I see a pump as a clear advantage.

I don't know what you mean by "external skimmers". I assume it's a type of protein skimmer and not a surface skimmer.

Basically I think it's fairly obvious that more return flow means more filtration. A sump is essentially a filter, bigger filters with more flow, filter more water quicker.

I see sumps as a drip catcher for filtration devices, not as filters in and of themselves. Sometimes less is more. You never gave any reasoning or linked any sources for the 10x turnover you feel so strongly about. Why not 40x if you want to do it all with one pump? That way your drain will not need to be vented and you wont get the salt spray and suction sound. There has to be reasoning why a particular turnover volume achieves a dynamic equilibrium.

A typical skimmer is independent from return flow and will essentially work the same regardless of return flow (in limits).

Very few if any protein skimmers cannot be operated on a two compartment FIFO system as I have described above. Even a becket skimmer with a high volume pump can be plumbed with the effluent line directed to a second compartment so skimmer treats new water first.

If you compare two scenarios with the first one delivering 2500 GPH to the sump drawn over a 12" x 6" overflow, then a second system where only 1000 GPH was drawn over the same overflow and delivered to a sump. The second scenario would have a higher concentration of surfactants due to a thinner film collected at the surface. It's the same argument one would make for a longer overflow box or removing the teeth from an overflow. Both scenarios keep the protein skimmer fed with fresh water. The first version moves some extra water that doesn't reach the protein skimmer. If you don't use a FIFO method, the 2500 GPH system will process the same water over and over with greatly diminished efficiency.

There are many ways to skim the cat, but you must use a method that assures that the protein skimmer is fed pre-skimmed (highly concentrated/protein-rich water) and skim it only once before returning it to the tank where it mixes with unfiltered water.

Eliminating or reducing the need for additional power heads or closed loops is also a big plus in my book and I believe it results in a simpler system. You can increase in tank flow all you want but if you're limited by return flow your filter is also limited, higher return flow will not only keep particles and matter suspended but it will also filter them out faster.

If your gola is to eliminate closed lops and power heads than you will need a 20x turnover rate, providing your flow dynamics are good, and they will be limited by only surface draining.

Not everything rises perfectly to the top of a tank and gets filtered out through the overflow in real life. Surface skimming is always going to be limited by blocks we install to prevent creatures from escaping and high total tank flow keeps things mixed up. I've also seen surface skum build up problems with lower flow tanks.

I wouldn't use teeth on an overflow for this reason. Horizontal barriers placed parallel to the overflow (above it) will keep out fish and inverts without breaking surface tension or reducing overflow surface area. Plastic gutter guard placed vertically inside an overflow box will serve the same purpose.

This is where a closed loop system offers superior flow dynamics. A return and intake can work together to build up inertia (kinetic energy). Closed loop intakes can be located in areas where detritus settles and inline mechanical filters can be used to collect it. Closed loops also offer a back-up system for flow (gas exchange) if sumps run dry, pump failure, or while you are servicing the filtration in the sump or feeding.

Using a one pump system with a 10x turnover ratio will not adequately keep detritus suspended, create ripples on the surface, keep the whole surface moving, and reach all parts of the reef structure.

Well your science isn't that scientific, it's really just an opinion based on your own experiences and some information from various sources, just like mine.

It isn't really my science, I quoted a number of very reputable sources and I showed the math. You didn't explain your experiences and you didn't show the math or even a link to the source of your magic number of 10x turnover. If you need me to back up anything I have said with scientific information than I will be happy to. I am also willing to listen if you can find fault with any of the specifics of my logic.

To me turnover means the flow turned through the sump. Pure closed loop, in tank flow doesn't really turnover anything. I prefer to practice around 10x turnover with additional in tank flow if required, many times this is not required as tank demands are based on coral species kept. I've gone into as much detail as you have on this subject, perhaps it's split between two threads but it is there. The problem is it doesn't really mean anything without evidence to back it up which is why I for one look at other peoples experiences as well rather than being blinded by my own.

The point her is simple. Why do you move water to and from your sump? The purpose is to give the filtration devices unprocessed water to clean. If your devices operate best at 3-5x the flow of the tank, then the other 5-7x you are moving is simply a juggling act. If our goal is to use our resources wisely, then we need to put more thought into magic numbers.

I appreciate that you have found this 10x formula to work best for you, but you don't have me convinced that you have had less success with 3-5x turnover or with a closed loop system (greater than 10x).

Well I for one do enjoy reading TOTM profiles, I think it's interesting to see what successful tanks use for equipment and I think a lot can be learned from other peoples experiences. Taking ideas from a group will almost always produce better results than taking ideas from one individual. I'm not sure why you would consider such a thing dishonest, perhaps the parameters aren't always that accurate but the equipment and healthy corals looks awfully real to me.

I treat TOTM's the same way I treat a show & shine car show. It's nice to see success and a well groomed finished product, but I prefer to follow the learning curve as the transmission comes out and you pass around the greasy factory manual as you come up with innovative modifications. I learn more from forum discussions about what does and doesn't work. I learn more from failures than triumphs, but it doesn't stop me from enjoying a mint TR6

Well I guess we're opposites which is probably why we get along so well , I consider myself smarter than I am experienced. I have an engineering degree and I believe I pick up things faster than most people. Where I lack personal experience I have to rely on other peoples experience to fill gaps when necessary.

I would have gone easier on you if I had known you had an engineering degree working against you

I'm not asking you to explain the logic behind a 10x turnover ratio just to be a smart ass. I would like nothing more than to be proven wrong and learn something new. Heated debates on forums are my only chance to win an argument. I don't stand a chance with a debate with my wife