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Sk8r
10/16/2010, 10:58 AM
Just a note for those contemplating buying a tank.

Plexi is far cheaper, lighter (especially important in larger sized tanks). It is dead-simple to drill for bulkheads and connections.

Downside: plexi will slowly, over time, bulge and maybe split seams, if not adequately braced. Beware any tank or sump with a raw plexi edge. Braced tanks cost more, and there's a reason.

Plexi scratches so easily that a grain of sand caught in a cleaning magnet can scratch it. Algae will then grow in that scratch and become a PITA. Cleaning plexi is harder. You have to be very careful. When you get an algae film or a coralline buildup on your 'glass' it's quite hard to clean off without scratching it. And you WILL have algae.

Beware of odd-shaped tanks---the weirder the angle of a seam, the more likely it is to come apart when full of warm, very heavy water. I had a neat skinny but tall (6') one that had only one seam. It became pear-shaped and split when used as a fish tank. Coffee table tanks, etc, are also suspect.

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Glass doesn't bend, is far harder to scratch---you can use a single-edge razor blade to clean it in a snap, and you're not going to scratch it accidentally.

Downside: Glass is pricey.

THIN glass, bargain tanks, particularly, but even better tanks, can break, especially if hit by a rockslide. I put a bottom piece of plastic lighting grid (eggcrate) over my bottom to hold my rocks in place and prevent any sharp single point resting directly on the glass.

Downside: glass is heavy: my 54 gallon tank weighs 80 lbs empty. Glass is harder to drill, and there is an outside chance of breaking it during drilling, esp if this is your first try.

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Again, both are good in their own way---but pick your downside. And whether glass or plexi, BRACING is a good thing.

I am the owner of an unbraced, raw-plexi-edge sump, and I have found a way to stop it bowing, just as an FYI: I got some U-shaped aluminum channeling to put along the top rim, with a notch in one side for the baffles. It was a less expensive sump: I went with cheap, then got a problem. But the aluminum edging, painted with white refrigerator epoxy, does seem to do the trick. File that one away in your personal data bank should you ever have the problem.

99mstng
10/16/2010, 11:57 AM
Great write up . . . I have never had plexi tank before but did have a sump that eventually warped from what I though was heat. My lfs told me however it was likely just a poor design.

Jeff000
10/16/2010, 01:29 PM
FWIW, Plexiglass, Acryilic, and Lexan are all different.

The biggest problem with the plastics is they scratch so easy. Lexan would be the best plastic, but its more expensive then glass.

Glass has different qualities too, they are not all created equally.

Also remember the stand for a plastic tank needs to support the entire base, and with a rimmed glass tank it just has to be linearly supported, ie just the ends, or middle.
Glass does bend too, just not an easily measurable amount. A high speed video of an impact on glass will show the glass flex before breaking, its quite need.

discus510
10/16/2010, 01:40 PM
i dont know.. i just think its ur point of views or wat u think
glass does scratches and once it scratch u cant fix
glass cost more than plastic?? yes depending on which type
if ur goin with a standard glass tank tats 180 gallon or an acrylic tank tats 180 the acrylic will cost more. now if ur talkin about custom with starphire glass all around is a different story. i have never heard of a plexi tank with leaky seam but i have heard lots of stories of glass tank havin leaks from seams and all

Sk8r
10/16/2010, 03:07 PM
The combo of heat and weight of water will make the plexi bow. I had a really good one, and after 5 years, the bow was getting really scary. The little sump that's giving me a problem right now has started by popping the seam in a baffle, but not in the corner. Yet.

Definitely there are a lot of grades of material: a Starphire glass tank that's half an inch thick can be quite, quite heavy for its size. Lexan is nice if you can go that pricey. It's a case of what you can afford---and if you know you are economizing on your choice, just be warned, and be careful with it. Never be cavalier about a rockslide, or preventing one; don't use inappropriate scrapers, and take as good care of your tank's integrity as you can. If you know you had to economize severely, start a replacement tank piggy bank and keep feeding it.

[If you're curious what my own biases are: My advice if I were advising a friend who had the funds and who was picking out his 'first' tank would be: go plain-shape, a tall rectangle, put a high fake rim on it (prevents jumps without a lid)---no filter, just live rock; get good but not crazy lighting, keep basic corals AND tough fish, to see how you like it, get a glass reef-ready 50-gallon if you can, because that lets you keep more kinds of things; get a reef-ready 75 or 100 if you really love tangs more than anything, because you need the room; arrange to have a 30 g sump below with a fuge, and get a decent but not too spendy skimmer. That kind of rig can get you into the hobby without too much trouble, let you keep most things, and is something you can easily sell off and get a little of your money back, and some of what you have can be upgraded into a larger rig if you discover you'd rather have a tank than a sofa.

Jeff000
10/16/2010, 05:25 PM
i dont know.. i just think its ur point of views or wat u think
glass does scratches and once it scratch u cant fix
glass cost more than plastic?? yes depending on which type
if ur goin with a standard glass tank tats 180 gallon or an acrylic tank tats 180 the acrylic will cost more. now if ur talkin about custom with starphire glass all around is a different story. i have never heard of a plexi tank with leaky seam but i have heard lots of stories of glass tank havin leaks from seams and all

Ok besides that being painful to read what are you saying?

Anything that scratches glass will scratch plastic far worse. Can you fix a scratch in plastic sure, but then you create optical distortion as you are just buffing it out, making that area similar to a lens from glasses. Plastic is also thicker then glass for a given size of tank, again effective optical quality.


Any tank can and will leak. Do a search on here and you will see leaky tanks.