215g Aquarium rebuild - post crack

The catastrophe...

Empty Aquarium
It's a sad sight indeed... what was a newly planted tank just a few weeks ago failed in the most unexpected way.

Crack in overflow box
The bulk of the back glass had rock glued to it per the details in my aquarium blog. This is a photo of the top of the overflow box, where you can see a serious crack.

Rear view of tank with crack
This is a photo from behind the tank, showing the full extent of the glass failure. Luckily the leak was fairly limited. Apparently the cedar supporting the tank held gallons of water in the grooves that were cut into it. The leak did leak to the neighbors loft downstairs, through the floor I guess. Luckily it didn't get next door, and since the unit downstairs is a yoga studio, we avoided damaging any expensive furniture or equipment.

On top of that, my LFS had a fire the same week. I had hoped to be able to order a new tank through them at or near cost since I do so much business with them. Alternately, I planned to check out their custom build costs. But both of those options are now out for the foreseeable future.

The rebuild...
After the shock and disappointment wore off, I decided that this would be an opportunity to fix some of the errors and design problems that existed in the original build. Specifically I determined that my filter capacity was much too light for the volume involved. The tank seemed to be a bit too tall on the stand I built to service it easily. While my CO2 reactor worked, it had a slow water leak and was somewhat weak compared to the rest of the system. The reef style overflow box and my use of it for locating the heater and intakes for the bog area proved troublesome.

After much shopping around, I narrowed my choices to a DAS 220g tank because they offered matching welded steel stands with leveling feet, and a tank from GlassCages.com which would allow me to get StarPhire glass at a reasonable cost. Since DAS never got back to the manager of that store with a price, I guess I'm going with Glass Cages. I selected a 72 x 30 x 25 240g tank with Euro-bracing, starphire glass front and drilled holes. The tank is slightly shorter than the 29" tall tank we have now and an extra bit of depth can't hurt for aquascaping purposes.

Drilling locations
I plan to have five holes drilled as shown here. The tank may have only two top braces, so I have requested that the holes be positioned under the braces wherever they are located. The middle hole is for a drain for water changes. I plan to use the other two bottom holes for returns. While I considered GlassCages' horizontal overflow boxes or freshwater overflow boxes as they referred to them, $180 seemed pretty steep for that. A friend who recently opened his own fish store, setup his display tanks with a PVC overflow design I plan to duplicate. He attached a 90 degree elbow to the bulkhead and put a filter cage on the open end. Rather than positioning the elbow pointing up as you would expect, he positioned it between one and two o'clock, basically at a 45 degree angle. This creates a skimming action in a simple way. The only concern is introducing air into the system as I won't have a sump. But I believe that because the elbow is angled into the water, the edge in the water can be lower in the water and thus allow more water over the edge than a typical upright skimmer.

Instead of the two cannister filters I had before that got me maybe 600gph combined flow, I'm planning to construct a filter setup with 1" PVC plumbing and a pump that should let me achieve 1200gph under load which should give me the desired 5 times per hour turn rate. I'm thinking I will go with mechanical cartridge filter and heater modules from Lifeguard and then go to a fluidized bed filter and back into the tank. For CO2 I thought I would switch to a venturi injector.

I saw in the mamouth aquarium thread mention of Ocean Clear filters. Is it worth it to use the Ocean Clear 340 rather than the AF-94 Triple Mechanical cartridge filter which is half the cost?

I understand I should look for an opaque FBF as the bacteria doesn't like light. That aside, the one in the catalogs has a negligible price difference between the models which cover 300, 600 and 900 gallons. While the smallest should cover it, is there any harm in getting a larger one since it's nearly the same price?

I also understand that FBF's can be a problem if the power fails, as your bacteria can begin dying off immediately after the substrate settles. It appears that the model here has four ports. Would it be worth using two to put it inline with the filter, and the other two to create a short closed loop with a small pump that can be run on uninterruptable power supply that can keep the sand in suspension in the case of a power outage? That also raises the question, how do I clean the cartridge without stopping the filter? Create a bypass loop?

Rather than running separate pumps as before, I thought I would just "T" off the return for water going to the bog area. I don't know if any products support it, but should I go larger than 1" pipe? I have read that I need at least 1" to get 1200gph. I guess having 1" returns doesn't require having minimum throughput.

Because of the bog area, I will lose CO2 faster than normal. In my original reactor I tried to get the pH down to 6.15 from the 7.5 or so it stabilized at pre-CO2. I had planned to return it to 6.8 or so before I add fish, but I don't think I got it down to 6.15 despite running a steady stream of bubbles 24/7. If I put a venturi inline after the filter elements, will that be enough or do I need to pump it into a reaction chamber? If I need a reactor, is there any point in using the venturi or could I just pump it into a reaction chamber?

Lastly, I heard that MagDrive pumps basically last forever. But apparently the QuietOne pumps are very good and are more energy efficient than many others. But the smaller ones I got for pumping water to the bog didn't seem terribly rugged. The cost is comparable, which should I go with?

I'm going to try to find someone to make me a steel stand with leveling legs. I really believe my stand had nothing to do with the failure, but the floor isn't level and the tank really should be. I can probably build a wood stand to compensate for the floor, but since it's not adjustable, if it was moved at all, it would be off. I'll probably lower the aquarium and bog slightly to make it easier to access. I'll probably leave the lighting at its current level since it's quite intense.

Before I set this project in motion, is there anything I have overlooked? Anything I should consider revising?

Thanks.

Michael