Jump to content
Innovative Marine Aquariums

Flood risk design considerations


C-Rad

Recommended Posts

Someone asked me this question privately, and I wanted to post my answer, and see if the community had anything to add

 

Is it possible to have a sump and be worry free of any type of flooding onto the floor?

There is of course no way to make flooding impossible, but you can be "worry free" if you reduce the risk, and/or the impact, of a flood to the point where you choose to accept the small risk and stop worrying about it.

 

To reduce the risk of a flood:

1) At each design decision point, consider leak risk. Glass or Acrylic? (Acrylic is safer), Sump or AIO (AIO safer); Glued PVC joints or hose/barb connections (PVC safer). Use known best practices: Drilled overflows instead of siphons, don't depend on check valves, float switches, sensors, etc.

2) Design in redundancy so that two things have to fail at the same time to cause a flood: Have two overflows, in case one clogs; use a pair of float switches where one would suffice, etc.

3) Consider designing in a fail-safe. I once had a system that was bottom drilled and had all plumbing and filtration housed in the stand. I sealed the lower 10" of the inside of the stand so that it could hold water and ran a drain pipe from the bottom of the stand out through the wall of the house. Any water that leaked into the stand would drain outside the house, so the only risk left was that a tank seams might fail or that an earthquake could knock the tank and stand over. Water from any other failure would just drain outside.

 

To reduce the impact of a flood:

If you live in an apartment and have downstairs neighbors, a tank flood could cost you thousands of dollars (high impact). If your tank is in the garage on a concrete slab, the impact of a flood might be zero. Try to arrange things so that the impact of a flood would be minimal by providing a harmless place for flood waters to go. If I had downstairs neighbors, I would build a shallow catch tray out of a 4' x 8' sheet of plywood rimmed with 2x4's. Such a tray, when screwed together, varnished, sealed, and placed on the floor under my tank stand, could hold about 60 gallons of water, and a lot of peace of mind. I'd have to learn not to trip over the 4" tall wall on the floor around my tank, but if my tank is < 60 gallons, I'd sleep "worry free" (a bargain I think).

Link to comment

Just to add.

 

on a siphon based system;

 

1)Make sure the Sump has enough room to take whatever water can drain from the DT if the pump goes out.

2)Make sure the pumps in the sump are high enough that if siphon breaks they will only pump what the DT can handle before overflowing ( if pump runs dry it may burn out, but is better than a floor full of water)

 

If you follow these two guidelines the overflow should never flood (ofcourse theres always the chance that a seam or connection could leak)

 

I like your idea of building a box under the tank, I might have to explore a way of doing this within the stand so as to conceal it as much as possible.

Link to comment
Just to add.

 

on a siphon based system;

 

1)Make sure the Sump has enough room to take whatever water can drain from the DT if the pump goes out.

2)Make sure the pumps in the sump are high enough that if siphon breaks they will only pump what the DT can handle before overflowing ( if pump runs dry it may burn out, but is better than a floor full of water)

 

this.

 

and:

 

3) have an emergency drain - an open standpipe that will let loose more water than the return pump can push. this is not entirely necessary if #2 is followed but were not talking about necessary. were talking about worry-free redundancy.

 

and primed and glued PVC is the absolute safest method of plumbing. I learned the hard way that you should always use what seems like too much teflon tape in threaded fittings. and hose barbs that will never be wet (not the return pump) should use those steel hose clamps. those things will keep your hoses on real good B) . anything else should use a plastic hose clamp if youre worried about it.

Link to comment

Here's my 2 cents wort of cut & past

 

 

To start let me come right out with my bias is towards drilled tanks.

 

Link to bean animals silent & fail safe drain.

http://www.beananimal.com/projects/silent-...low-system.aspx

 

 

So first as to how & why.

There are only two ways of taking water from one tank to another. Well three. But we're not counting buckets. It can be siphoned or allowed to flow throw a drain.

 

There are pro's & cons to both. But let's start with siphons. Others may disagree about the order of importance. but for me the ability to drain a large volume through a relatively small drain would be at the top of the list. Others would be simplicity, mobility, & ease of use. Now the main problem is that they will lose siphon. This is not a question of if but when.

 

Which bring us to the alternative. Drilling the tank. First putting a hole in the side of a tank means that its almost guaranteed to have the water come out of it. Now the problem with that is you may not want the entire tank to drain at once. As a solution we utilize overflows to wall off the majority of the tank from the drain. But we'll talk about those later. Now as I said its almost guaranteed to drain. Which means that it could become clogged. But that's the only way to prevent the drain from working. As a solution we add secondary drains to work as back ups. Just in case. Which means that you no longer need to worry about wet floors.

 

 

What size holes do I need for the drain and the backup?

 

1.) To start there is a relationship between drain size & flow rate. Flow rate is acheaved by the height of the water line above the drain, combined with the size of the drain. I.e. The more water & the larger the drain, the greater the flow.

 

2.) How much flow is wanted through the sump/fuge. There are great debates over what is the ideal flow, but a fuge needs a high dwell time for nutrient transfer. So maby, as much as it pains me to use the term, 5xthe size of the fuge for turn over. Flow can be met by powerheads. Simple sumps have no limitations on there flow behyond micro bubbles, heaters, & skimmer performance. In the over flow thread there I have a link to a flow rate calculater. I'll see if I can add the link here with the blackberry if not will do later.

 

3.) More than likely it will be either a 3/4" or a 1" drain, pearsonaly I like to use the same size drain for both drains. But here's that relationship coming back. As you move the drain closer to top of the tank, the less flow it can handle. So the backup has to be able to handle grater flow than the primary if & when the the drain clogs (Yes the drain will clog). This helps to set where the drains will be Placed. The distance between, height within the overflow, & so on. The back up needs to be low enough to drain while still not having the overflows water line go above the weir (you knew I'd work it in there some how, fancy word for were the water flows over). While the primary needs to have enough distance between its self & the backup to be fully submerged with out creating a vortex sucking bubbles into the drain (that's what makes noise).

 

4.) When drilling tanks. There needs to be, at minimum, the diamiter of the hole between the hole & the edge of the panle being drilled. This is the minimum to not crack the glass. More is better. So figure out how much you want through the sump/fuge. Then put the backup as close to the weir as you can & still achive this flow. Then put the main as low as you can with out cracking the tank. Set water line in overflow with ball valve or gate valve.

 

What size hole for the return?

 

1.) This will most likely be the same as the output of the pump. Would expect 1/2" or 3/4".

 

2.) 3/4" or 1" return plumbing can be split then reduced to 1/2" as it enters the tank.

 

3.) Without siphion brakes, or other messures to prevent backflow. The tank will drain to these returns when the pump is shut down.

 

What pump recommendations? (I'll be running an MP40 for the main tank flow)

 

1.) Normally the least expensive to run. I hate spending money I didn't need to. I run quiet one pumps for this reason. But to be dead silent eheim is supose to be the best. Untill you steep up to exo's like iwaki (the pretty japaness one) or gen x (the knock off)

 

2.) Eductor nozzles can reduce the size of pump needed to reach a set flow rate without effecting the drains. (Free flow)

 

3.) Never reduce the flow to a pump this will cause the pump to cavatate (bubbles).

 

4.) When picking the pump remember to judge it not only on flow rate but head.

 

What plumbing parts do I need to pull this whole thing off and where's the best place to get them?

 

1.) Welcome to the never ending trips to homedepot. Most plumbing will be found at the local box store. Speicalty items like bulkheads will be at the lfs.

 

2.) Peaces parts Vynal tubing Hose barb fittings (sevral types. 90? Mpt for the main, reg mpt's for most everything else)A couple feet pvcTeflon tape (this is your new best friend. Use a lot & once you have tightend the fitting will need to be replased if lossened)Bulkheads & screens (no open pipes)Pvc solvent90 elbows & other pvc partsBall valves/gate valvesQuick conects/true unions

 

3.) Air leaks will cause asperation (bubbles) make sure to have all joints sealed tight.

 

There are pics of my old ten x ten in my tank thread & more info on water in my sig. Hope this helps.

 

 

 

 

 

Then in response to using a wave maker in a tank with an exo overflow.

 

 

well its kind of catch 22. as you can guess, any type of overflow will be problematic with a wave maker. but the coast to coast can handle it better than others as long as your ok with a few things. the waves will reduce the effectiveness of its skimming capability's. this is why most chose this type of setup. but the water will also be agitated mixing the surface skim into the water column. so this is not as large a factor as it could be.

 

another thing to consider is that. with a wave system the water will not flow into the overflow at an even rate regardless of type. the water is either moving towards or away from the weir at any given time. which is why as long as the water is moving along the weir there is some benefit to the coast to coast setup. this though can bring its own problems.

 

ok so with this in mind. know there will always be a noise issue combining an overflow & waves. the water flowing into the overflow at varying rates will set up a wave in the overflow itself. internal overflows are not as affected by this in a negative way, as much as exo's. due to the water volume inside the tank helping to hold the overflow in place. where as an exo if made without proper planning may not with stand the force's this places on it. both of these limits can be met by using a smaller wave.

 

with the setup you were looking at i would expect it to be fine as long as you didn't go nuts with the wave action. Ive never used anything but the vortechs to make waves but it should be the same.

 

 

Will be editing to include items from previous posts. If as always some one can think of something I've skipped speak up.

 

teeth or toothless overflow

 

Ck what you got to throw in.

Link to comment
  • 3 months later...
This is an important issue for anyone building a tank stand to understand:

"Joint" - The method used to fasten two pieces of wood together where they intersect Uusually at 90 degrees. Since a tank stand needs to support a lot of weight pushing directly downward, the important joints are the ones connecting the top (weight bearing) horizontal pieces to the vertical pieces (legs).

 

"Butt Joint" - Where the horizontal piece rests directly on top of the cut end of the vertical piece, as was done with this stand. With butt joints, the tank weight is pressing straight down, compressing the wood. Wood resists compression very well, and so this kind of butt joint is extremely strong, and won't fail until the force pushing down is so great that it crushes the wood, or causes the vertical piece to bow and then snap. A 3' long vertical 2x4 can support many thousands of pounds before it bows or fails. The bottom line is that if you use butt joints, the wood will fail before the joint fails - extremely strong. (This is called "compressive strength" (tensile strength is different))

 

"Lap Joint" - Where the horizontal piece is screwed to the side of the vertical piece. With a lap joint, the weight pushing down on the top horizontal pieces, is trying to either sheer off (break) the screws that hold the end of the horizontal piece to the side of the leg, or to rip the screws out of the wood. The compressive strength of wood is much much greater than the "shear strength" of the screws, so the weakest link in a lap joint is the screws (either breaking, or ripping out).

 

Butt joints are far superior to Lap joints for supporting heavy weight (like a tank stand). Lap joints usually work because even though they are much weaker than Butt joints, they are usually sufficiently strong to support a tank. That being said, I see no need to use Lap joints for tank stands, and I would never recommend them because there are just too many ways to do lap joints wrong, and end up with a stand failure. Here are some of the ways to get in trouble using lap joints for a tank stand:

1) If the wood around the screws gets very wet, the screws can pull out much more easily.

2) Screws can rust eventually (and invisibly), and rusty screws break rather easily.

3) If you use weak screws (like drywall screws) for a very heavy tank, you could exceed the screws shear strength.

4) If you only use one screw per joint, you could exceed the strength of the screw.

5) If you use screws that are too short, and go through the horizontal piece, but don't go very deeply into the wood of the leg (like 2" screws), they could pull out easily.

6) If you drill too large a pilot hole for the screw, and it's threads don't bite deeply into the wood, they can pull out easily.

If you use butt joints, there's really only one rule to remember to avoid a failure:

There must always be a vertical column of wood, composed of one or more vertically stacked pieces, supporting each end of each weight bearing horizontal piece.

It doesn't matter how you connect the pieces, as long as they can't shift out of position such that they no longer form a "vertical column". With butt joints, the fasteners don't support the weight of the tank, but only serve to keep the pieces oriented in a vertical column. The vertical columns of wood (resisting compression) is what supports the weight of the tank. The fasteners only need to be strong enough to resist the relatively small forces that will try to knock the frame pieces out of vertical (bumping the side of the stand, moving the stand, sliding the stand along the floor, etc.)

 

Butt joints have one weakness compared to Lap joints: A lap joint between two 2x4's using four screws, will usually resist "wracking" better than a butt joint. Wracking is what happens when a 90 degree joint hinges, like an elbow, and can be pushed to be more than or less than 90 degrees. Any amount of wracking will cause the "vertical" legs to tip, stop being vertical, break the one big rule, and let the stand fold up and colapse. The easy fix for this is to skin the frame, and let the skin firmly fix the joint at 90 degrees. Another way is to install diagonal cross pieces at each corner, turning each corner into triangle, or "skin" each corner with a little plywood triangle.

 

I think the two best design principals when building a stand are

1) use butt joints instead of lap joints.

2) Prevent wracking at each 90 degree angle (in both the horizontal and vertical planes) either by skinning, with diagonal cross pieces, or with little plywood triangles.

 

 

I should add that while the stand in this thread is a great example of using butt joints, there is one joint that, would be a bit weak if supporting an acrylic tank (but this stand is for a glass tank, so no problem). The cross piece that connects the middle of the two long top horizontal pieces doesn't have any legs under it, so if there were a lot of weight pushing down on it, that weight woudl be supported only by the sheer strength of the screws holding the cross member to the horizontal pieces. For an acrylic tank, I would either put legs under the ends of the cross piece (2x2 legs would be more than enough) or I'd use metal joist hangers on each end of the cross member. For a narrow tank I'd just use 3/4" plywood or the top and let that support the weight of an acrylic tank.
Link to comment

Archived

This topic is now archived and is closed to further replies.

  • Recommended Discussions

×
×
  • Create New...