Ok, let's restate the goals of this build so the sump design can be validated.
- No water changes (1/year maximum acceptable)
- Minimum maintenance requirements
- Enjoyable view of fish & plants
Breaking these goals down...
No water changes
- Time-consuming - deal breaker for owning a tank
- Messy and a hassle
- Automating this is not possible (at this time)
- Tasks that must be performed to keep tank in a livable (to fish)/enjoyable (to me) state
- Acceptable maintenance tasks: cleaning glass once/month, feeding 2-4 times per week, adding water every 2-3 weeks (evap), clean mechanical filtration once/month
- Two hours/month is acceptable
- Tank is in a family area, makes a relaxing view, conversation piece
- Tank is also next to my office desk, so helps make work enjoyable
Based on my experience thus far, it's clear to me that these goals are 100% attainable with a little research and design effort. My sump has worked very well this past year, but the jump from 50G display to 125G display should be taken seriously. A huge amount of water in there, and a lot more to go wrong.
So...we've established that display is 125G, sump will be 50G, and if possible, incorporate the 30G, giving us ~200G of water in the system. Let's look at the plumbing first, since before we deal with filtration, we need to deal with moving water safely and continuously through display/sump/refugium.
Plumbing - Overflow design & drains
I'll be re-using the Beananimal setup from the 50G...good thing I went total overkill on that build (it was expensive, however). According to a number of overflow calculators, I require the following:
- System throughput: 1200GPH (two pumps, probably after losses more like 1000-1100GPH)
- Overflow minimum: 18"
- Minimum drain size: 1.43"
The Beananimal system (Herbie +1) gives me 3" of drain right off the bat, plus an additional 1.5" in the emergency, so with a safety factor of 3x required drainage...we good. If you are not familiar with the Beananimal system...google it already. Big props to Beananimal for taking the time to document/draw in CAD. System works exactly as specified.
The overflow sizing, however, will be 18" exactly...on the 50G it was 36". I am not anticipating issues, but this is an area where more research is required - consequences of too short an overflow. Guessing just a thicker weir, perhaps more noise...?
At any rate, the rest of the design will be identical to the 50G. All bulkheads and whatnot will be re-used...gaskets should be fine, less than a year old and have never leaked. I'll need to drill the lid so I can get the secondary siphon tube through the top, that's about it.
Plumbing - Return design & pumps
My setup today uses two return pumps, one at 750GPH, one at ~500GPH (IIRC), both with 3/4" outlets. The lines are PVC today with loc-line for adjustments in-tank. Further, the returns are 'through tank', something I thought was awesome, but ultimately is a bad idea, especially in a 125G unit.
The flaw is simple - if your ball valves fail and you start siphoning, your returns are mounted below the water line (1-2") and so you suck back into the sump that much water (in the 50G, ~3G). Not a huge deal until you realize that your overflow still has to empty (1-2G), and what if you've just topped up the sump? Several gallons spilled. Wife not pleased.
The fix is running the returns over the top of the tank, through the lid, and using 'siphon breaks' (holes drilled in the return like 1cm below water line). Since I have the ability to drill glass, no biggie...this is what I'll be doing. Further, no more ball valves. So rattly and annoying for something that 'might' work.
The one area where I've struggled is with the return flow pattern. Some people use fan attachments to spread the water out, others spray bars. In my case I used the normal cone-shaped spray pieces, pointed them at the front-middle-top of the tank (returns located at either end of the tank), and lived with a turbulent center and weak back edges.
Anyways...I am thinking since the drain/overflow will be at one end, I'll try doing dual spray bars mounted vertically, one at the front, one at the back.
Plumbing - Sump design
The sump in this scenario performs a few functions:
- Mechanical filtration (big coarse filter pad)
- Biofiltration via biofilter media (pot scrubbies in my case)
- Additional water volume helps make parameters easier to handle
- Provides a place for submerged equipment to live, thus better display tank view
The mechanical filtration is aided somewhat by the 'gutter guard' placed on the overflow (prevents fishies from getting sucked down), but is mostly there to deal with excess food, stuff kicked up from substrate, etc. I tried filter socks, but they got clogged up way too fast...I don't need that level of filtration, anyways.
Biofiltration is pretty straightforward...lots discussed on this. Pot scrubbies are the generally accepted 'best bang for the buck' biofilter media - this is not a luxo-bling build, and with 50G I have tons of space to play with.
Additional water volume...yep. 50G is additional. Not sure how much water the Rena Filstar XP2/XP3 units hold (used on the 125G by previous owner), but it sure ain't 50G. More like...2G. No wonder he used a UV sterilizer.
Keeping the equipment below also means it can be shut behind padded doors, so you cut out even more noise. If I had blingy mag-drive pumps (and no ball valve nonsense), the system would probably be near-silent.
The design itself...I'll probably just keep the same idea, but double or triple the pot scrubbie count. Gerry's (barrreport.com) sump has a nice feature where water is trickled onto his biomedia - something I attempted to duplicate (with spectacular failure) - so if anything, this would be my next experiment.
Plumbing - Refugium design
Ya no clue on this right now. Not even sure the tank will physically fit.
Plumbing - Conclusion
We good. Except for overflow width concerns. And fitting the refugium. And designing the sump.
It's my build thread, and I'll write a novel if I want to. K?