energy efficient HUGE tanks?(long)

[dendronepthya]

I was brainstorming ways of making a 1000 gal. tank. I saw in person Mr.4000's tank up in Michigan, and when he told me how much his electricity bill was per month, I nearly hit the floor. He also doesn't do water changes on his tank which is something I can't live without. Once you factor all that in, huge setups are more of a pain(financially) to keep running rather than setting up. I would like a HUGE tank someday, but I do not want to create an albatross that will cause me to make significant sacrifices elsewhere.

This is an idea that I came up with. First of all, the tank I was thinking of making is a 72"x72"x40" reef pond made of concrete with four acrylic windows. The tank will be located in a sunroom where it gets a lot of natural sunlight, and the plumbing will lead to a large sump in the basement. I plan on sealing the inside of the pond/tank with fiberglass. It is the most expensive option, but I do not want to take any chances with a leak or a break.

First of all, lighting a reef can be the single most expensive part of maintenance. I don't think that I can really avoid it, but this is an attempt. I would light it this tank with 4 400W 12K halides, and rely on natural sunlight for the majority of the time. The 400W halides would be responsible for actinic-like supplementation only. I am assuming that each halide can cover a 36"x36" area if they are raised high enough over the pool. Although the tank is 40" deep, I plan on an exceptionally deep sandbed of about 10" or so. That would mean that the light has to penetrate 30" to get to the tank's bottom, and with natural sunlight doing the bulk of the work, I think the halides can do the job.

The sump as I mentioned will be located in the basement. Doing a quick mental calculation, I figure a 1000 gallon concrete tank full of water and a 10" sand bed weighs approximately a billion lbs., and I won't be able to have a basement directly underneath it. So, I will have to stagger the lower level of this fictional house so that the tank can lay on the ground, and the basement will be offset slightly.

My thinking was, since the sump is in the basement, the tubes leading down into the basement are essentially downdrafts. Why not use the gravity of the water coming down from the overflows like a downdraft skimmer? I would like to have one of the two(?) overflows hook into a HSA1000 type beckett skimmer. By doing this, I would essetially be eliminating the need for a large pump(going back to the energy efficient idea). The other overflow tube can go straight to the sump and act as a safety drain incase the skimmer gets blocked for some unknown reason.
I am a big fan of Algal Turf Scrubbers. I was thinking of having the skimmer output lead to two dump units that empty into the sump. Again, I would be eliminating the need for a pair of pumps. The only thing I would really need is a large pump to get the water back into the tank/pool on the floor above, but I would have to get one anyhow.

Wow, this has turned into a very long post. I am curious as to what you guys think about a setup like this. I am not so much bothered by initial cost so much as I am maintenance costs. Thanks for reading this

 

[Anonymous]

Well since the house is still fictional you may want to worry about taking the house-buying step first!

Many of the other considerations will rely on the particulars of the house...

 

[percula]

1. The HSA skimmer wouldnt work by gravity feed.
2. Filtered Natural Sunlight can/will cause unwanted algal blooms.
3. FIberglassing the inside of the tank isnt the best way, it would be epoxying the inside. Dont worry, a properly setup tank thats made of concrete isnt going to break.
4. Algal turf scrubbers, ok, but throw a huge skimmer and a refugium if ya have to and get rid of that high expense.
5. I agree w/mathguy on this one, hey why did you change your name anyways mathguy?

 

[Anonymous]

<BLOCKQUOTE><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><HR>Originally posted by percula:
<STRONG>5. I agree w/mathguy on this one, hey why did you change your name anyways mathguy?</STRONG><HR></BLOCKQUOTE>

"I am what I eat" - he he, cheese sandwiches are my favorite snack.

Anyways, the name may have changed, but the same smooth taste is there as always!

 

[dendronepthya]

percula,

Thanks for the comments. Now for a few questions.

Why doesn't a beckett style skimmer work with gravity feed? Is it the water pressure issue? I think that water traveling down a 10 foot 1" pipe into a beckett would have more water pressure than a quiet one pump. Maybe some fluid mechanics person can chime in on this issue.

There is quite a bit of difference between a refugium and skimmer compared to an ATS, but I won't get into that here. ATS can be manufactured at home. I bought one a while back, and will likely make huge ones at material cost for a setup like this.

Also, the natural light thing. Why do people still think that sunlight=algae bloom? If you maintain a low nutrient reef, you will not get those algae problems regardless of what kind of lighting you use. Has anyone been to Tropicorium? They have roughly 40,000 gallons of saltwater there lit mostly by sunlight(it's a big greenhouse), and they do not have algae problems. I'll have to respectfully disagree with you on that point. I have seen nothing to make me believe lighting spectrum has anything to do with algae outbreaks if nutrients are tightly controlled.

Yeah, the house is a higher priority, but this is all still in the brainstorming phase.

 

[Anonymous]

I use a gravity fed skimmer and it works quite well, very well in fact. Here's the design.... very very simple!

 

[Len]

dendro & percula,

A HSA will work under gravity feed, so long as enough pressure can be generated that water flow through the downdraft/beckett is constant and strong. This can be easily engineered to work.

UV filtered natural sunlight won't cause any more algae blooms then artificial lighting, given the same quantity. Light is light for most shallow water organisms. As long as certain nutrients are controlled (and temperature-related problems), natural sunlight is arguably the best light source. You'll really need to design a good ventilation system for that sunroom/greenhouse, or else it'll get really hot and humid.

 

[KenH]

The largest tank I have seen in person was a 1400 gallon tank. It was constructed of concrete in a square which measured about 8' on a side. The corners and based and top trim where poured concrete sealed with epoxy paint. Four 8' x 4'(or so) glass panes were fitted in each side. This sounds very similar to your idea.

All overflow and return piping was handled in the center. The end result was an incredible 32' of viewing window. If I were to attempt such a project, this is the way I would go since it gives you so much more aquascaping potential than you get with a one or even 3 sided rectanglar setup.

This tank did not get natural sunlight (it's in Portland OR, so we don't count on the sun too much around here). Seems like that technique should work in an area that gets sun 300+ days a year or so.

I thought a tank like this could be setup really cool with each of the 4 faces showing a different biotope. High energy reef face, soft coral dominated back slope, lagoon and estuary or similar.

Course it might be cheaper to move to LA and buy a house with a pool, go out and buy 32 gallons of chlorine remover, 3200lbs of salt and you are in business.

--- Ken

 

[Anonymous]

<BLOCKQUOTE><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><HR>posted by KenH:
Seems like that technique should work in an area that gets sun 300+ days a year or so.<HR></BLOCKQUOTE>
Reefs in the Pacific can go very long periods with very cloudy weather. I really do like the biotope idea, been daydreaming about that for a long time now.
dendronepthya, why would you want any form of actinic supplementation? As a firm supporter of natural sunlight use in reeftanks, I can tell you that its more gorgeous than any artificial light source, and if you are specifically replicating a high energy zone such as a reef flat, your depths would likely be close to what can be naturally and frequently found in the Pacific.

 

[dendronepthya]

galleon,

I agree that naturally lit tanks have a very attractive look. I guess the reason I was thinking of using mh's to supplement the real thing was to give the corals a bluish highlight. In the evenings(which around here are at about 6pm), I still want to be able to see the stuff in the tank, and I kind of like that "actinic" look.

 

[Anonymous]

ok, I gotcha.

 

[Minh Nguyen]

You still need a pump to pump water back from your sump into the main tank. you can't get away from haveing a big tank and not haveing big pump.
Natural light is great. You will need to worry about the heat associated with natural light. Most of the tank with natural sunlight seem to have a large volume of water out of the sun (like a huge sump) or else your tank will heat up very quickly with mid day sun. Some sort of cooling is needed.
You will need to bugget about 1 dollar per gal per month. This is my experience with my 400 g tank. Maybe a little less if you use natural sunlight.

 

[914]

for least energy usage, it would be best to have the sump's water level be the same (or only slightly lower) that the tank's anyhow.

the point is:

when the water falls to the basement sump, it gains a lot of kinetic energy. that energy is lost to friction, either in the pipes on the way down, in a skimmer, or ultimately, when it splashes down into the sump.

in order to get that water back up to the tank level, you'll have to put *back* in (in terms of pump) ALL of the energy that was lost, plus the friction inherent in the plumbing on the way back up.

there's no way around the fact that by dropping the water all that way, you'll just have to pick it up again.

most efficient would be to have the sump at the same elevation as the tank, and then all of the pump's energy input would go towards making current in the tank, versus just pushing the water uphill first. (minus plumbing friction, of course)

your skimmer would still need it's own pump, but the total energy requirements would be a LOT less.

but... for a *truly* large tank, why use a sump at all? simply partion off part of the tank, and run your stuff in there. a shelf to hold the skimmer at the right height, and your pumps (if internal) or pump pickups (if external pumps) plus heaters, etc.

the idea of a 4-sided tank with a plenum or space in the middle is a good one. you could set the water level in the middle/center section to be only a few inches below the rest of the tank, and the rest of the tank overflows into it. then, the pumps only have inches or so of head pressure to work against, and friction losses are reduced because the plumbing is so short. automatic water-topoff, heaters, chemical bags, algae farms, refugia, dosers, whatever.. it could all go into the middle-of-tank 'sump'


the only issue is access to the sump. with a tank that large, i'd guess a catwalk that extends out over the tank would be necessary. you'd have to lie on your face and reach down into the sump to work on it.


as for lighting... probably the best bet to get natural lighting in there is to use a skylight and a large mirror, on gimbals with a computer control. the several advantages of this are:

1) smaller skylight area needed. only as large as the surface area of the tank.

2) better lighting year-round, particularly in northern (southern) lattitudes. the computer will postion the mirror to reflect light as efficiently as possible, all day long.

3) the mirror can be larger (parabolic, ie collect more light than normally would fall on the surface area of your tank) than the tank, increasing the light available.

4) the mirror computer can be interconnected with both auxilliary lighting systems and with temp controls. if the water starts to overheat, the mirror moves the light off the tank. if there's not enough light (photosensors at waterlevel), it can turn on supplemental lights.

5) with enough light, you can grow a lot of macroalgae, reducing or eliminating the need for skimmers

cooling....

i see two low-cost methods to cool a tank like that....

first is evaporation. if your area has relatively low humidity, then a well-ventilated tank room along with a lot of fans blowing on the waters' surface (and maybe even water sheets running down thin plates, at an agle, with fans) will drop the temp quite a lot. you'll have to have a largish RO/DI setup or whatever to keep the water level/salinity constant, but remember also that the water being added will be cold, and will help out.

critical to this idea are:
1) surface area of water. tricks/devices can be made to dramtically increase the surface area of the water.

2) airflow at water surfaces. fans.

3) relative humidity of the atmosphere around the tank. ventilation of the room/house would be key, and general humidity in the area/climate is important. lower humidity is better. if you've ever heard of a 'swamp cooler' then your climate is probably good for this.


the other option is ground-coupling.

this has a higher failure danger, as it involves pumping tank water through a large coil of tubing that's buried underground.

in any part of the country, if you dig deep enough (depends where you are), the ground temp will be around 55deg F. laying a large coil of thermally-conductive tubing in the ground (and probably covering it with sand, to increase thermal conductance and reduce chance of mechanical damage to tubing) will get you cooler water.

the ground *will* heat up, as it absorbs tank heat, but it will be dissapated as well. you'll need a civil engineer to tell you how fast this can happen, and how much tubing/surface area you'll need for your required temp drop.


just like the lighting, this should probably be computer controlled, with a conventional backup system, in case of extreme temp swings.

another thing to be aware of is slab cooling effects.... if this tank is poured concrete, and it is sitting directly on the ground/slab, then it will conduct heat away all on it's own. how much depends on the kind of concrete, if/how much insulation was used when pouring it, surface area and local climate.


this whole project is something that it will pay you to do the math on...

you'll need several sorts of engineer to do it right, and make sure you don't make a mistake that makes the tank unusable/hard to maintain.

 

[fudge1]

Dendro,

Im sure a 10 foot drop in a 1" pipe will not be enouph pressure to run a beckett,and having also to split the pressure between two to four heads (wich would be required for that size of tank) will give you even less pressure.

You can test by capping and drilling a hole about the same dimensions of a beckett or similar style injector in a 10 foot 1" pipe,to see the pressure it will create.

You also reduce pressure greatly if the skimmer intakes are not directly below the display tank,by having any 90`s,tee`s or 45`s inline on its way to the injectors.

If you are able to upsize the pvc from the overflows to the skimmer,say to 2",the pressure(weight)in the pipe will be much greater.
Also,have each injector fed by its own overflow from the tank,and any bends inline to the skimmer should be done as high up as possible,so there is more weight(pressure)on the injectors.

Just a couple o thoughts,Marc.

 

[percula]

Ok, I gotta see a bullet (beckett) working on a gravity feed, I feel there would be too much back up. Not enough force. Must also have constant water level. As for the ATS, I feel they arent as best a method, though I have seen a few in working order. They are an ok form of filtration, as my opinion is off, I would go with a skimmer and Ca reactor. If I had a big enough skimmer I would quickly incorporate a refugium. I feel that a refugium placed properly (although not in this situation) Is a much better method than an ATS. Yes, there is a big difference, and thus my opinion dictates towards the clearer filtration option. I just dont like the yellow, none clear, particles floating... Seen few that look like Id want. Yes, of coarse, I understand, that properly filtered unfiltered glass through which sunlight will flow through will not bloom if controlled properly, yet, I have yet to see one that uses this method where they do it right. The ones I see that work, Im ont getting into. Anyways, what equipment do you have now that you can use to ease this into creation? What do you plan to keep? Water motion would also be key = BIG pump, or surge? Anyways, have fun and a good weekend!

 

[Anonymous]

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[Diablo]

I want to do much the same sort of thing. I had planned on doing all things suggested by 914 except the ground-coupling (which is a rather good idea).

I agree with ditching the basement sump. It would need a BIG pump that would possibly eat more $$$ than your lighting.

The only other suggestion I can offer is consider a different kind of pump. Centrifugal pumps sit somewhere in the middle of the pressure v's flow table. There are pumps called axial-flow pumps (a.k.a. propeller pumps) that are 5X..10X better at moving water for the operating $$$ so long as the head pressure is only a couple of feet. They are just like a boat propeller in the middle of a tube.

 

[perclown]

I never like the sump idea. It's waste of energe. In return, you get noise problem because of the friction and water drop, and, of cause, the big utility bill. However, sump does have some major advantages, e.g., it keeps the water level constant at the main tank, and allow top-off equpiments etc.. away from main tank. To have the best of two worlds, this's what I did: My sumps, 10g+ 60g, are at almost the same level as the main tank, 150g.
My sumps are sittting right next to the main tank. (You need to have room for this kind of setup.) Water overflow from the main tank to the first 10g sump( 3" water drop), and, then, cascade to the 60g main sump(4" water drop). As a result, I hardly can hear any noise from the circulation between sumps and main tank, and the whole sump systems require only one RIO 600(25W)pump to drive.

 

[Anonymous]

Perclown-

I don't know about you, but I have to haggle with the wife for every square inch of floorspace I use for tanks - lord help me if she wants such-n-such chair in the corner there instead of a tank, etc. The side-by-side sump would be tough to pull off...