I think it has to due with the fact that acrylic can bend/bow if not fully supported on the bottom. I have an acrylic tank and, for some reason, the top has become bowed so it is convex and the light will wobble when it is touched. I attributed this to the fact that I put the aquarium into a "buit-in" wall niche that I assumed would provide enough support.

thank you. i wonder what exactly is so specific about support then (at the bottom). i am thinking a table sturdy enough to suppport a glass one will probably not properly support an acrylic in that respect. but how, the question remains! maybe a solid bottom?

other than that, do you like your acrylic? fresh or saltwater? does it scratch as easily as i hear?

Buy a stand with full support on the bottom and you will have no problems.I have a seventy five gallon tank that I bought in 1987 that looks nearly as good as when it was new. Always clean from the bottom and use an algae scrapper for an acrylic tank.

In Aust all tanks sit on a solid base plus a 10-20mm sheet of polystyrene sheeting.

Regardless how a tank is made it should be supported correctly.

Keith

Acrylic tanks don't need a stronger base but the bottom must be supported or it will bow. I've seen the front of the tank bow on a 300 gal acrylic. I guess the acrylic wasen't thick enough. Glass is much cheaper and doesn't scratch as easy as acrylic. Only drawback to glass is it's heavier.

I like my acrylic tank; it's a 35 gallon hex and looks really cool in the wall niche. I do not like the extra care acrylic requires. I bought an algae scraper that is safe for acrylic but it totally sucks. I usually use a cotton washcloth to wipe the algae off, then I wrap the algae scraper with the cloth to reach the lower depths of the tank and I use the scraper only around the seams. I also do not like how the bends of the acrylic distort my fish.

My understanding is that acrylic tanks are better if you want a large volume tank (I don't know the cut-off, probably 75 gallons), if you go with glass on a larger volume then it is thicker than with a smaller volume. If you do want a large volume, you have better clarity with a thinner-walled, acrylic tank. Acrylic tanks also come in many shapes (hex, bow front, cylindrical, custom) whereas glass is usually just your standard rectangle.

As far as weight goes, once you add the gravel and water, the difference between the weight of an acrylic tank vs. a glass tank is not very significant.

these are all very good points. i will consider all, and comment soon when i have time (i was just checking in since responses were emailed to me).

please continue! :)

I have only had small acrylic aquariums 10g and smaller. If an acrylic tank bows it is not made with the correct type of acrylic (cell cast I think) or thickness. Acrylic is stronger in ways that it doesn't shatter. The biggest complaint I,ve heard is about scratches, or having to take the extra care not to scratch. One nice thing is it can be drilled easier for overflows or plumbing. There is a formula about thickness of acrylic and height of the tank. If I can locate a link I'll post it. Also, kits are available to buff out scratches, again the maintainance. One thing I do like about acrylic is clarity, no green hue and seamless. I think my biggest gripe with it is the price. Another thing to consider is the size, I've noticed that they are somewhat different then "standard" so things like lighting and canopies can cost more also. A nice middle of the road is a bowfront glass tank.

melle, when moving a tank weight matters. My old 150 gal glass tank needed 4 guys to carry, my 240 gal acrylic needed 2 guys. Acrylic is the strongest where the corners are glued together, thats the weakest point with glass tanks. I think the largest 'standard' glass tank is 150 gal, acrylic maybe a better choise over that.

James--good point about moving! :-)

Woe--disappointing to hear my tank was possibly not made right, it was not cheap. I always thought it was because I put the tank in a spot that wasn't designed for an aquarium.

Either way, I agree that the bowfront glass tanks are nice. If I had the space that is what I would prefer; if I ever get the space, I'd sell my hex and get a bowfront.

Woe--disappointing to hear my tank was possibly not made right, it was not cheap. I always thought it was because I put the tank in a spot that wasn't designed for an aquarium. --- Sorry, I assumed it was the front of the tank that was bowing (is that even a word?) I didn't pay close attention to the above. Some manufacturers will not warranty acrylics that aren't placed on a full bottom stand. Thickness goes as follows for tanks under 8' in legnth: 1-12" height, 1/4" thickness, 12-18" H, 3/8", 18-24"H 1/2", 24-30"H 3/4". One more con of acrylic that I just thought of since melle brought it up- sometimes the tops are not fully open as with glass. Alot of larger acrylics have framework over the top which can sometimes limit size of decor, like roks and type of filtration to be used.

"sometimes the tops are not fully open as with glass. Alot of larger acrylics have framework over the top which can sometimes limit size of decor, like roks and type of filtration to be used."--- i just noticed htat while looking on ebay. seems pretty inconvenient to me but it must add to the strength. i didn't notice that at the pet store since a canopy was on top. since i am not looking for anything larger than,, say 125 :) though not likely, glass may be a better choice for me.

i like the idea that acrylic gives better clarity but i am confused by "I also do not like how the bends of the acrylic distort my fish." (melle) is that because it is bowed?

thank you, keith. this is something i only heard of in the last year. never heard of it before until the wonders of the web.

woe, the bowfronts are nice! however, they do not look much different at the 55 gal size, even kinda funny to me. now, the corner bowfronts are another story and i haven't seen a bow larger than 55.

acrylic price will stop me for sure. the drilled holes make me nervous, also. how do these work again? i know hoses or fittings go through there, but how does it not leak? i am a little gunshy. a 25 gal leaking was bad enough to deal with.

if i do go with acrylic, it would be a good used tank and not new. a new price just is not possible. perhaps 75- 125 in glass isn't very different from acrylic. however, the jury is still out so keep talking please! i am sooo indecisive!

The corners on my hex tank distort the fish, most likely because of the angle the acrylic is bent. Bowfronts don't distort but give (at least to me) the perception of a panoramic view. They seem to have a better sense of "presence" than a regular flat front tank.

I agree that the tops of the acrylic tanks can limit what goes into the tank, can limit how you set up your filter/heater/air lines and can make the tank more difficult to clean.

thank you for that clarification :)

If cost is a factor glass is the only choise. The standard sizes [rectangular shape, normal deminsions]are the best values. The best buy is probably a 55 gal. After 17 years I had to replace my Perfecto 150 gal tank, a new one was $400 [much thinner glass than original]. Buy new if possible, and from a well known manufacture [Perfecto, All-Glass], one leak will more than offset any savings from a used tank.

One nice thing about the 75G is the legnth, 48", exactly the same as inexpensive shoplights and bulbs from home depot or the like. The 75G is wider then the 55G so you have more room for decor and plants giving it good depth perception.

i have kept my eyes open for used acrylics. but, i still cannot grasp the holes drilled and how that works without leaks.

anyway, it seems that all glass 90's MAY be on sale at an lfs next month. i am crossing my fingers for a good price.

Alot of large acrylics don't have a completely open top like glass tanks. There is sometimes a kind of "rim" arround the top. You may have to drill to allow access or filtration or other equiptment. Also, a popular option for a larger tank is a wet/dry, sump, or refugium filtration system. These types of filters usually require an overflow of some sort. The most efficient way if to drill a hole in the bottom corner(s)of the tank and build an overflow "bulkhead" arround it. It then drains into your "filter" , usually another fish tank with media or various other things, then a pump in the "filter tank " returns water to the aquarium. Nice things about these "sump" type filters is you can place equiptment like heaters in there instead of the "main tank" , also it is a place to keep "feeder fish" for carnivores . You can also factor the amount of water in the sump to your fish per gallons total, example 90 gallon tank + 20 gallons of water in your sump = 110 gallons. Glass tanks can also be drilled but a special drill bit is required or have a LFS do it, i they provide that service. Just a small plus for the DIY' er w/an acrylic tank.

ah, the sump. thanks woeisme. that is the part i was talking about. how does one keep water from leaking out of the holes in the bottom? thy brain doth not comprehend!

how does one keep water from leaking out of the holes in the bottom? A bulkhead fitting. Usually made of PVC or similar quality plastics. It is not unlike the plumbing fitting that connects a sink basin to your plumbing drain. I know you have limited website access, so do a search on sumps, trickle filters, wet/dry or refugiums. They are somewhat similar systems mostly. Or check out drsfostersmith.com and search there or store bought versions. They are pretty easy to make. One o the simplest versions I've seen used a plastic storage bin and those plastic 3-drawer things sold with storage bins. Until you see a picture its kind of hard to describe.

ah-ha! thank you! i always see the parts list pictured in catalogs but nowhere have i seen them put together and "applied."