MMcDonald 285 gallon Plywood Build Thread

Good summary Matt... and exactly the challenge...

Mr. Janes called me back today... great conversation, I wish I could've recorded it to study it more.... this guy REALLY knows his stuff.

A point... at eductors to increase velocity...

Big point... pick yor coral live stock first... then design your flow. He designs his tanks down to the placement of the coral in the tank and then designs the flow of the tank in an area to match the flow needs of that type of coral.

He also very generously gave me access to a private library of research articles. I now have months of reading....

I am 100% convinced that mass water movement and velocity are the drivers, not turnover rate.

More to come,
M

 

That is a great point. And as you and everybody knows - that takes great discipline. We all start out idealists in a since, then we step in that fish store and see something and everything changes. That aside, that is probably the best approach.

I look forward to reading more. In the meantime, I will try and track down this one design I mentioned... it is very old though - hopefully I will find it.

 

I have been spinning on how to divide a tank and get the flow I want. Originally, I liked the idea of a long tank with a end overflow. what I'm trying to think of now is how to have an end water box divided from the live stock for suction and discharge.

To place a pump under the tank takes some 90s, then the flow has to come out of the floor. Trying to think of a closed loop sucking and discharging from the end. Using MP40s on opposite ends will work too. I was also thinking how to make a "flow box" at one end. Say water enters at one side, then have 3 or 4 high flow prop pumps in in line to suck from one side and discharge in the box setting up a flow. But then reversing flow would be a problem unless you did the same thing on the other end with opposing pumps. Only problem is I don't know of any prop pumps to work. Something like a stripped down Korilia magnum.

As far as natural water movement, surge or wave motion are natural ans act in a scrubbing motion. The gyre article was good at pointing out natural currents in reefs... mass movement. So using power heads to blow water in a chaotic manner seems good, but still nowhere close to wave motions and mass flow.

Closed loops seem to be quite a chalenge. MP40s would work well, but you would need 2-4 on each end and double that if you wanted the ability to reverse. They are a little complicated and I'm not totally sold on their reliability. However, they move a crap ton of water with the lowest energy use and heat input. Say on a long tank put two on one end on the front side of the end, with two on the opposite end on the back side of the end. So you would have a push across the front and back. But 4 MP40s cost $1600. However, you can sync them up and put them in reef crest mode and not only would you get a mass movement, but also a surging component. Now to reverse that you are talking $3200. Still not sure how many I would need on my 60x30. Two would put out 6500 gph of flow in a 185, but obviously I have no idea what velocity of movement I would have.

So McDonald.... in your conversation or reading, just how important is reversing flow. Seems like a cool idea in terms of like tidal flows, but currents don't reverse. Reversing flow doubles everything and makes it quite complicated. Curious of the actuall benefit.

 

We didn't talk about not reversing at all, but we did talk about the frequency. He said the frequency of reversing didn't matter much.... 5 minutes versus 1 hour. He really impressed that it was all about velocity and mass movement. I am thinking reversing isn't at all important.

M

 

So then what about flow velocity??? It's easy to say turn over rate, but not too sure about how to figure out how to get into that sweet spot of velocity between 15-22 m/s.

I was looking into Tunze turbells today. The 6105 kit with 4 heads and controller was $1600. That's 4x 3200 gph. If reversing is no big deal, then that would be a lot of flow for a 185. A lot of money too.

Personally.... I don't have a hang up with powerheads. MP40 look real nice just cause they are so cool. Others are a little ugly, but some folks don't like the look. Personaly, a reef tank in a living room is artificial to begin with, so I don't really care about how "natural" it looks. The Bahamas look "natural". Unfortunately I don't live there and they won't fit in my living room.;D

When I look at big pumps to move a lot of water in a closed loop...Reeflow Orca.... not a lot of flow compared to propeller pumps, and they use about ten times the power. I'm not too sure I want to do a closed loop on mine, so I'm stuck with MP40s or Tunze streams.... but both are very nice water movers.

 

The research he gave me to read is all about velocity and how much required etc. After I read that, I'll report back.

M

 

Feel free to pass on the hook up.

 

my thoughts exactly