I have lurked for a long time, and made a few posts here and there along the way. I recently completed some renovations for my 75 and thought I'd post what has been done.
First the tank parameters
75 gallon tank
2 54 w T5 w/Gieselman bulbs (Fish Need It)
Pressurized CO2 w/PVC reactor
Eheim 2028 filter
Fish - 7 Bolivian Rams, a number of tetras, 4 corys, and 2 plecos
What were the issues?
Symptoms were excessive detritus build up, and BBA problems in the slower moving water. Also, the lighting never seemed to be enough - basing this on a previous tank lit with PC lights. Research indicated two possible issues with the fixture - poor reflector and bulbs too close together.
I won a second Eheim 2028 filter at an auction, and ordered two reflectors from Reef Geeks and started planning my course of action. I am a hobbiest woodworker and had a bunch of oak...
First I attacked the hood.
The first challenge is that the hood is 48" long but the tank is 48 1/2" long, so I had to find a way to make the vertical supports angled, or I would need a lot more wood.
The supports have dados cut into them which the hood sits into, and rabbets cut on the bottom for the tank frame to fit in, keeping the hood from moving. This one somehow shifted during clamping, and is off about an 1/8th of an inch.
The hood is a basic box measuring 48 inches long by 15 inches wide, and 5 inches tall. The legs add another 6 inches of height. The main box is made of 5/16" oak and the top is a piece of luan plywood. There are 4 supports oriented vertically in each inside corner. Additionally, there are 4 cross supports attached to the luan for additional support for the reflectors. The molding is homemade from other oak stock, made with several passes from a couple of hand planes. The finish is thinned polyurethane in three coats.
Rather than throwing good money after bad, I decided to try to reuse as much of the Fish Need It fixture as possible. It turned out that all the electrical components were reusable. The reflectors are about 9" apart, and the box containing the ballasts was easy to attach to the rear of the hood and can be seen in the end view below.
I wanted to add the second Eheim, and provide redundancy to the CO2 reactor, so a couple of trips to Lowes for PVC resulted in this.
With the ball valves, either filter can power the reactor, or the reactor can be isolated from either.
The plan is to keep both intakes in the back left side of the tank, somewhat behind the stump, and have one outlet as a jet pointed along the top rear of the tank, and the other be a spraybar under the surface pointed left to right to create additional current.
My original plan would not fit, so the final version of the manifold incorporated some changes, but it all fit. However, the second Eheim did not come back to life when plugged in, and a quick inspection found a cracked impeller.
The lights do a much better job filling the tank with light despite being 5 additional inches higher. The light is much more evenly distributed, and the plants seem to pearl more since installing. How well the current helps move the detritus will remain to be seen once the new impeller is installed tomorrow. I am happy with the look of the hood, and have a much better idea of the clearance I'll need when I build a new stand and canopy in a couple of years.
If anyone gets this far, apologies for no closer pictures of the tank, my iphone did not take good ones and I was too lazy to bring out the SLR.