Cylindrical Acrylic Aquarium

[skywindsurfer]

So the guy said that he's still trying to find an 'oven' so that he can bend the acrylic. We have the material, so as soon as he gets this 'oven' issue situated, he can start building. Still no word on the bimacs , though I hope that I hear something this week.

 

[skywindsurfer]

I have the 1/4 hp chiller on the 250 tank right now. The temperature dropped almost instantly from 80 to 78. After I move the tropical animals out and switch out the pumps I'll see how far it will drop the temperature.

 

[skywindsurfer]

I've managed to pull the majority of fish from the 250 gallon and place them into the 40 gallon along with all of the corals and a few inverts. All that's left in the 250 gallon is the stingray, lunar wrasse, bird wrasse, pinfish, and four damsels. I'm still working on catching the last four damsels and moving them over. I'm not sure what I'm going to do with the wrasse because I can't put them in the 40 gallon. The pinfish will be fed to the large blue crab in the sump, and the stingray will stay in the 250 gallon(probably along with the two wrasse.) My controller for the chiller works, but will not turn the chiller on. As soon as I can get that working I'm going to re-arrange the rock work and switch out the large pump with the small pump again and run the chiller on the 250 gallon to see how low I can get the temperature without running the chiller 24/7.

 

[Joe-Ceph]

Well the wife drew the line and said no for the 1/2 hp but aggreed to let me get a 1/4 hp drop in for about $75. Only catch is it doesn't have a thermosat.

That's a good deal for a 1/4 hp chiller, even without a thermostat.

My controller for the chiller works, but will not turn the chiller on. As soon as I can get that working I'm going to re-arrange the rock work and switch out the large pump with the small pump again and run the chiller on the 250 gallon to see how low I can get the temperature without running the chiller 24/7.

Look at the amount current your chiller draws (amps or watts) and make sure that your thermostat is designed to handle that much load. If not you'll either need another thermostat, or you can wire in a relay that is able to handle the load, and run the relay off of the thermostat.

A 1/4 HP chiller is probably a little weak for a 250 gallon tank, but you will be able to use it if you don't add too much heat via pumps and lights, and don't allow too much heat to leak in through the tank itself, by insulating it. I recommend setting the tank on top of 1.5"-3" 3M "Styrofoam" brand insulation board. It has an R-Value of 5 per inch, which is great, and can easily handle the weight of the water, which is only about 1 to 1.25 pounds per square inch. You will probably also need to cover the tank completely for security reasons, which will create a nice air space above the water, which will insulate the top of the tank. You can use the Styrofoam board also on the back,and sides (must be pressed right up against the glass, so no moist air can get in between and cause condensation. You can find some flexible insulation to cover half of the side of the curved tank. If you don't sufficiently insulate the tank, your chiller will probably run too much, and beat itself to death (or you'll need set the tank temp too high)

 

[skywindsurfer]

A 1/4 HP chiller is probably a little weak for a 250 gallon tank, but you will be able to use it if you don't add too much heat via pumps and lights, and don't allow too much heat to leak in through the tank itself, by insulating it.

I figured, but last time when I put the small pump on, lowered the temperature in the house to 70F, and just ran the two 48" dual bulb T5 fixtures I managed to get the temperature of the tank down to 72F I think it was. So I'm hoping the chiller wont have such a difficult time with that.

I recommend setting the tank on top of 1.5"-3" 3M "Styrofoam" brand insulation board.

Easier said than done. The tank when empty is a couple houndred lbs, and where will I put 200 gallons of water and 200+ lbs of live rock while I try and slide some foam under it? It's half inch thick glass. I would have to wait to do that if I were going to move it again. I'll just leave it be since I'm getting this new tank soon. (that is if my guy can ever find an oven to bend the acrylic)

You can use the Styrofoam board also on the back,and sides (must be pressed right up against the glass, so no moist air can get in between and cause condensation.

You might want to see the way we have it set up lol.

If you don't sufficiently insulate the tank, your chiller will probably run too much, and beat itself to death

That's what I'm worried about.

 

[skywindsurfer]

I got the controller for the chiller working and switched out the pumps. The temp dropped from 81 - 79. We'll see what it drops to tomorrow.

 

[Joe-Ceph]

Nuts! You want your tank viewable from both sides, AND you've got a big sump. That tank will be difficult to insulate. You could still insulate the bottom of the tank from inside the stand, and you could insulate the sump, but if you can get it down to 72, you can limp along like that until you get your big round tank up. Design your stand for the big round tank with the idea of having 2" to 4" of Expanded Polystyrene Insulated Sheathing under the tank (maybe cause the walls of the stand to rise high enough to hide the layer of insulation). I like DOW's "Styrofoam" brand, but others will work. I find it easier to work with, and not as crumbly (messy) to cut. It costs about $25 for a 4' x 8' sheet 2" thick, and 4" will have an R-Value of 20, which will make a huge difference.
To do it right you would also want to plan to insulate the curved walls of your tank. The circumference of your tank will be about 16 feet, so if you bought 16 yards of black vinyl at the fabric store ($50-$60) you could sew together a "bag" that would cover half of the surface, and put pink attic insulation inside it (or a flexible foam mat). You should also make sure that your pumps are designed to be external, not submersible, or dual use. I use Iwaki pumps with metal housings, and I blow a fan on them to keep motor heat out of the water. If you do all of that your 1/4 HP chiller should be able to keep that beast down to 68 or so without working itself to death.

I found a source for foam sheeting HERE


The ultimate would be to get thinner sheets of acrylic and with spacers make the walls of your round tank double paned. That's not as hard as it sounds, but that's another thread. Let me know if you might want to go that way.

 

[Joe-Ceph]

In case you haven't thought about it yet, I think curved tanks give a distorted view. You can learn to ignore it for personal viewing, but it's hard (impossible?) to take clear pictures through a curved tank, so if you were hoping to document things, you might have trouble.

 

[skywindsurfer]

Yes I know about the distortion. I take care of a few curved tanks at work. It's not so bad. I turned the chiller off last night before I went to bed and when I got home today the temperature was at 77F, so it dropped two degrees without a chiller. I turned the chiller back on and we are heading to the pool. I check it again when I get back and continue to run it until I go to bed again. I'm just giving it a few hrs a day until I get the temperature down so I don't kill the chiller just trying to reach 69F. I figure I'll shoot for 69F - 70F as a stable temp. They guy is still working on getting an oven so he can bend the acrylic. He has some 1/2" material that he found in his shop and is going to give me a quote on. He can use 3/8" for $600, but priced the 1/2" at about $1,000 if he had to buy more material. Right now I'm still waiting to hear whether or not I'll get those bimacs. I still haven't heard anything back from my co-worker about that order. Like I said before, he told me he would let me know a week in advance when the shippment would arrive. If I cannot get bimacs then this is all for not lol. Still I got a nice chiller for 80 bucks.

 

[skywindsurfer]

So I got the temperature down to 75F tonight before I turned the chiller off just now. The house AC is set to 75F so I'm hoping that the tank will continue to cool past that.

 

[skywindsurfer]

So it stayed at 75F all night and day. I turned the chiller on again when I got home around 5:30pm and the temperature has dropped to 73F so far. I'll leave it running for another hour or so until I go to bed, but I think it's staying at 73F. I'm going to lower the house AC as well down to 70F to see how much that helps.

 

[Opcn]

skywindsurfer, I don't mean to be rude but you seem a little frenetic. In my experience that tends to not work out for the animals so well. I would highly suggest that you sit down with a calendar and lay out a timeline of what you have to get done by when, and try very hard to stick to it with out bouncing around off the walls. Large tank builds take time. If I were you I wouldn't expect to have saltwater in this cylindrical masterpiece until October at the earliest.

 

[skywindsurfer]

Well I would have to agree with you Opcn. I have always been a bit frenetic. I've alwasy been a spur of the moment kind of guy and I enjoy the flexibility of change. About every 3-6 months I change something, trying to make it better. And at this rate I might not even have my tank until Oct lol.(knock on wood)

 

[skywindsurfer]

They weren't able to get any octopus this order, so its back to the drawing board.

 

[Joe-Ceph]

They guy is still working on getting an oven so he can bend the acrylic. He has some 1/2" material that he found in his shop and is going to give me a quote on. He can use 3/8" for $600, but priced the 1/2" at about $1,000 if he had to buy more material.

I've never heard of anyone building a tank like this, but I can't think of a good reason why not, and I suspect that tank builders have just lacked imagination, so here's my idea:
The thicker your tank walls are the better (up to about 1.25"), so the more expensive 1/2" material would insulate better (sweat less), and bow less (top to bottom) than the thinner 3/8" material. However, since you're going to build a stand with a rigid flat top to support the tank bottom, Why can't the bottom piece be thinner (less expensive)? Since the top piece will have cutouts, it might pay to make the top piece thicker, but the bottom? If the bond between the wall and the bottom is done such that the lower edge of the wall rests on top of the bottom, there will be a 1/2" cross section of acrylic bonded all the way around, no matter what thickness the bottom is, so I don't see why the tank would be any stronger if the bottom where 1/2" instead of 3/8" (or even 1/4" for that matter). Maybe you should run that idea past your tank builder and see if he has a reason why you shouldn't do it that way, other than: "but we never do it that way".