Dual overflows on 10G?

[Mafioso]

I'm currently working on a 10G (UNS 30T) with a 13G Sump (Icecap 15 Reef Sump).

I want to use @Scorched design on this tank to keep things clean, using Lifeguard Aquatics bulk head kits with screens for the drains. My main problem is I'm wondering if dual 1 inch bulkheads is a bit too much for this style of tank? I know his design was based on the 12g long which has quite a bit of space between bulkheads (does this matter?). I'll be using a single 3/4 return due to the limited size of space in the tank. With my measurements I can fit a 1 inch bulkhead on each side and a 3/4 inch in the middle for return.

 

I don't necessarily have a problem with running a single bulkhead for drains but I figured 2 would technically be better.

 

Thoughts?

[mcarroll]

Definitely excessive, but if the holes are already there, then it's not your decision.  Are you drilling the tank, or are the holes already there, or...?

 

If it's un-drilled, then IMO a single 1" drain and single 3/4" return is still excessive (3/4 and 1/2 would be sufficient) so would be about my limit.  Running a return over the back isn't so bad either, so that could bring the number of holes in your tank down even more, depending on your tastes and ingenuity.  👍

 

If the three holes are already there, I'd almost be tempted to run the 3/4" as a single drain and use the 1" for dual-flow.  You'd be flow-limited by the 3/4" drain, but I bet that would still be PLENTY of flow for a tiny tank like this.   Having flow emanating from multiple directions is the basis for ideal flow in a reef.  👍

 

Food for thought, anyway!  🙂 

[Mafioso]

No, I'll be drilling the holes. I chose my hole choices from @wetworx101 calculations on depth, and am pondering using 2 holes for drains purely for redundancy. 

 

Drilling isn't an issue I've done it many times for terrariums. I'm asking this question mostly for redundancy incase one of the drains is blocked. I can decrease the size of the drains but from my research most advise against it due to the size of the hole. 

[mcarroll]

1 minute ago, Mafioso said:

No, I'll be drilling the holes. I chose my hole choices from @wetworx101 calculations on depth, and am pondering using 2 holes for drains purely for redundancy. 

 

Drilling isn't an issue I've done it many times for terrariums. I'm asking this question mostly for redundancy incase one of the drains is blocked. I can decrease the size of the drains but from my research most advise against it due to the size of the hole. 

(If possible can you link the resources you're referring to rather than (or in addition to) linking their avatar?  I'm not familiar with any of the folks you've mentioned so far, so I can't really comment directly on a lot of what you're talking about.  That said...)

 

The common thinking on drain redundancy seems to be a one-size-fits all approach that doesn't take anything into account other than a completely generic fear of maximum risk.  By that thinking you ought to be using all three holes for a Herbie drain setup, otherwise "you're asking for it".

 

If you can break away from that mentality, "more holes" only solves one "generic fear" and that's if a drain hole becomes clogged.  Something that's not really very likely in the first place....but let's think it through a little.

 

To begin with, your plan is already past that by using screens on the drains.  What are the odds that your entire screen will be blocked?  Even less than the already-low odds of an entire drain-hole being clogged.  Probably A LOT less...so you're approaching infinitesimal odds just by adding a simple intake screen.  

 

Even within that choice there are conservative and aggressive "pre-screening" options...

ordepending on what you think solves your tank's actual risk better.

 

The intake style and tank contents (livestock, mostly) than really matter in this decision...along with overall design.  FYI you can design a much more elaborate intake if you really think the risk is there....all connecting to one bulkhead.  The more surface area on your intake, the less the suction per square inch, the less risk of something large (or weak) being pulled to the intake.  Of course you want SOME things drawn in, so that makes it a balancing act that depends somewhat on overall design more than just the number or size of holes in the drain design.

 

The drains themselves (ie the hole and plumbing) should only have to be rated for the correct amount of flow, and the concern over them could end there.  (Not to make light of that....calculations for adequate drain capacity is a whole 'nuther area of thinking.  IMO play it conservative....50% or less of rated capacity for operating capacity.  Ie 600 GPH drain only carries 300 GPH or less in day-to-day actuality...leaving plenty of margin for error, as the saying goes.

 

The drain's intake is what needs to be blockage resistant...and the level of that "need" should be dictated by tank contents, etc.  What is the actual risk in YOUR setup?  It should be mostly predictable...and what's not predictable should be allowed to fall into the tank design's overall margin for safety.  (I think KISS theory enters here.)  👍

 

For example, if you're planning a coral-only system, it would be hard to argue that much is necessary for drain protection at all.  But if you're planning an Amazon Planted tank, I can see planning for large leaves to be "afloat" and possibly caught on a drain intake.

 

Anyway...if you can link those resources, I might be able to give a little more direct feedback.  👍 Tell me if any of that is useful or interesting.  🙂 

[Mafioso]

Here is the bulkhead calculations I'm referencing (sorry I'm new to this forum and his calcs seemed to be used quite often elsewhere when I was researching, you can also see within this thread that many don't recommend anything less than a 1" regardless of tank size, let alone a 1/2". Is this wrong?).  The drain covers have many reviews of them cutting flow quite a lot (I believe @Scorchedhad this same problem with his setup). I'm not worried about the return. 

 

 

[mcarroll]

Do what this fella did in that thread:

1 overflow + 2 returns

 

Some more numbers to consider in your design...this table has been floating around the internet for a long time:

 

Anyway, back to the link you posted...

You can see from the numbers in that post (good find, BTW....never seen that before) what I mean by 1" being overkill for a 10 gallon tank.  (Let alone two 1" drains!)

 

(This may be where those numbers originated... http://www.wetwebmedia.com/BulkheadFloRateArt.htm. Here they claim 165 GPH for a 3/4" bulkhead....still more than adequate for your 40 GPH.)

 

For a modern reef tank, all you need is about (4 x [tank volume] = ) 40 GPH to operate the filters/heaters/whatnot that will be in your sump.   That is plenty and you can, according to that post, easily get that through a single 3/4" bulkhead at only 1" depth.

 

In any case, assuming the numbers on that old thread are accurate (would be nice to know the origin of those numbers, but they at least seem to jive with numbers on that table I posted), you'd have enough reserve drain capacity to get actual flow as high as 190 GPH.  There's no real good reason to run that much flow through a sump however.  (The closed loop days are behind us.)

 

Still, there's room in a 3/4" drain to provide some supplemental display flow via the return, if you saw the need.  The only caveat is that you generally want SILENT gravity drains, and that generally means keeping flow around or under 50% of the rated capacity.   So practically speaking, you could run your drains at 100 GPH (which is 10X turnover, or more than double what's really needed for the sump) without affecting noise....maybe higher, but you'd have to test it to know.  Some noise is almost a sure thing as you get closer to 100% of the rated flow capacity.

[Mafioso]

I did notice that the turnover rate was a bit high but like I was saying with drain covers many people are seeing the GPH cut almost in half not including all the other little things in line to and from the sump that might cut flow rate.  I will also be using pvc flex tubing for 100% of the plumbing so we wont be having as direct travel as you would with hard PVC (not sure if that changes things since that chart is for PVC Sch 40, I think this may be more of an issue for noise?)

 

I do agree 1" seemed overkill for everything but reassurance for blockages which was my main reason for using 1", but I think you've convinced me to skip it in favor of 3/4".

 

Thanks for the detailed info, it really helps!

 

 

 

 

[mcarroll]

2 hours ago, Mafioso said:

I did notice that the turnover rate was a bit high but like I was saying with drain covers many people are seeing the GPH cut almost in half not including all the other little things in line to and from the sump that might cut flow rate.

I used "with intake screen" numbers, so (at least by the numbers) that's OK for your setup.   Rig up a PVC tee to your bulkhead and use two intake screens if you want dual intakes/less flow resistance/slightly more flow.  (And if you look at their intake screens in the test, they LOOK very restrictive – not like any screens I've seen before.)  Lifeguard's low-profile screens should be better – and their standard (longer) screens should offer very low resistance by comparison to the ones used in the testing.

 

Most other things (eg elbows, et al) make no difference in a short plumbing run like you'll have.   If your sump was going to be in the basement on the other side of the house, you'd want to account for all that distance and any curves taken.   freecalc.com has (had?) a nice friction loss calculator, but they appear to be offline.  (Gonna have to find a new calculator!!)  You can see an example I made for 3/4" plumbing using that calculator in this old post, just for reference:  https://www.reef2reef.com/threads/flow-calculations-pump-advertised-numbers-accurate.426905/post-4944514. (With a little search dillligence, you can find LOTS more examples I made.  This was just top of Google's results....not the best example.)

 

In a nutshell (see link) the example was this: 500 GPH through a 6' run of 3/4" PVC pipe along with a typical set of fittings for that run.  That only adds a virtual 1.3' to the run (7.3' total) in terms of calculating flow (aka head loss).  

 

If you look at published spec's for better pumps like Supreme Mag pumps (https://dannermfg.com/products/pondmaster-pond-mag-magnetic-drive-water-pumps see "Specifications" tab), they will have a flow chart.  You'd take this flow data from the calculator (7.3' virtual plumbing length) and the chart will tell you which pump.....in that example, a Mag 9.5 (aka PM 950) would be necessary to give you flow you want through the plumbing system you have.

 

This info is usually more useful on the return line where pipe size is usually more limited than drain size, but the same friction factors are at work in a drain.  It seems like the testing on that WetWebMedia link was trying to demonstrate these friction losses instead of calculating them.   Consider that their test numbers are only accurate for the flow rate and plumbing setup they used for their tests.   You'd have to extrapolate to your flow rate and your plumbing setup....or just use their numbers as a VERY rough estimate.

[mcarroll]

FYI, this calculator looks like an OK replacement....it also accounts for fittings.   I'll have to use it a few times to see if its results are good.  Let me know if you try it.

https://inventory.powerzone.com/resources/friction-loss-calculator

[Mafioso]

Gotcha, I'll do some testing over the holidays. I'll be sure to update you!

 

Thanks again.