San Diego Plastics

Acrylic Tank FAQ


  1. Acrylic tank questions
    by (Jonathan L. Burke) (Thu, 12 Mar 1992)
  2. The Last Word on Acrylic Adhesives
    by (12 Aug 93)
  3. Building tanks...????.....
    by (Wade Hines) (Tue, 16 Nov 1993)
  4. Building an aquarium (How to)
    by (13 May 94)
  5. Aquarium Photography - tips from
    by (Dave Chaloux) (24 Mar 1995)
  6. [M] Three-spot Damsel Spawning
    by (Dustin Lee Laurence) (11 Feb 1993)
  7. Transmission of glass vs acrlyic
    by ()
  8. Acrylic Maint.
    by ()
  9. Scratches on Acrylic: Help.
    by (2 Apr 95)
  10. Melting away acrylic scratches.
    by (Chris Paris) (11 May 1995)
  11. Need info on DIY acrilic tanks
    by you@somehost.somedomain (Your Name Here) (29 Jun 1995)

Acrylic tank questions

by (Jonathan L. Burke)
Date: Thu, 12 Mar 1992

In article <1021@proton.UUCP> () writes:
>Is my plexiglass tank bowing too much?
>I recently got a 50 Gal acrylic (Sea Clear) aquarium.  The plexiglass
>thickness is 1/4 inch on all surfaces.  When I fill it with sea water, the
>large surfaces (front and back) bow out 1/2 inch compared to the empty tank.
>Frankly, I am a little bit worried, this being my first plexi tank.
Up to 1/2 inch in the middle is normal for a 1/4 inch tank. Any more may
not be normal.

>QUESTION:is the bowing normal for plexi tanks,and does my tank flex more
>than others?  Is it in any danger of breaking?  Is 1/4" the normal acrylic
>thickness used on 50 galon tanks?  I am using it, but I'd rather empty it
>rather than risk 50 gal on the floor.

The risk is minimal - no different that any other tank (glass or acrylic).
1/4" is a normal thickness for a tank upto about 20" tall. 

There are many different grades of acrylic, all which have very different
properties.  This makes it very difficult to ask if any such number, say
1/4" is acceptable.  Be vary careful when you compare Glass to Acrylic -
the numbers really are irrelavant.  My company used 1/2" acrylic to make
30" tall 600 gal tanks.

Is this safe?
Is there any bow?
Less than most 5/8" plate glass tanks.  ie: my personal glass 220 (30"tall)
bows over 1/2" and it is made from 5/8".

>Costin Radoias, EE

If you have any more questions, I'll be glad to answer them.

Jonathan Burke
AquArt Custom Aquariums

The Last Word on Acrylic Adhesives

Date: 12 Aug 93


I just finished reading the adhesive section under ftp reefkeepers in the
diy section and realized that there is a lot of confusion out there. Since
I work for Rohm & Haas, the makers of Plexiglas, I thought I might
spread some light on the subject.  First let me say that I do not personally
work in the acrylic department, but have some experience from working with
people in that department and I am a soon to be materials engineer. Also,
my company is NOT liable for any of this information.

Acrylic or Plexiglas is actually PMMA (Poly Methyl Meth Acrilate). When
things are bilt with it, it is generaly not "glued" but solvent welded. With
glueing the adhesive itself forms the bond between the pieces and permanatly
stays there.Solvent welding actually works quite a bit different.The pieces of
Plexi are placed together in the desired fasion and the solvent is let to wet
or "bleed between the two pieces.  They are then left to cure.  What happens
is that the solvent dissolves the PMMA (in a small region).  The long polymer
molecules from each piece entagle with each other while they are in solution
with the solvent.  The solvent then slowly evaporates leaving behind a joint
of just PMMA with no adhesive.  The solvent we most commonly use is MDC
(Methelene Di-Chloride).  Also I wanted to note here that PVC "glue" is mostly
a solvent with some other additives and works in a similar fasion.  Again, I
am no expert craftsman with Plexiglas, but I do know someone that is.  I am
going to ask him if he wouldn't mind directly answering some questions to the
net, but I can't make any promises.  If he will, I'll post his logon ID.
Hope this clears up some confusion.
------------------------------------------------Frank Fatato             MAHFBF                                             "My man, pots
and pans"  J.M.                                    ----------------------------
My employer is NOT liable for anything posted here.

Building tanks...????.....

by (Wade Hines)
Date: Tue, 16 Nov 1993 (noel patrick moore) writes:

>Does anyone have any information on building tanks .
>I have been keeping fish for years and would like to start
>building my own tanks now.
>  What kind of glass is best ?
>  What kind of silicone ?
>Any information greatly appreciated.

Plexi-glass is best!

One 10'x5' sheet of 1/4" can be had near $100.

With this you can build a tank that with a 5 foot front and
20" x 20" depth and height. 1/4" will work but if you can
get 3/8 it's better but harder to bend.

A 8'x 4' sheet costs around $70. It can build a 4 foot by 16"
by 16" tank or other pertubations.

|                      4 feet                   |
|                                               |
|  1             Bottom                         |
|  6                                            | 16 in. 
|              !               !                |
|              !               !                |
|8             !               !                |
|              !    Top        !  Back          |
|f             !               !                |
|e             ! 4             !                |
|e             !               !                |
|t             ! f             !                |
|              ! e             !                |
|              ! e             !                |
|              ! t             !                |
|              !               !                |
|              !               !                |
|              !               !                |
|              !               !                |
|              !               !                |
|              !               !                |
|              !               !                |
|              !               !                |
|              !   16 in.      !  16 in.        |
|              !---------------!----------------|
|              !                                |
|              !   Waste                        |
|              !                                |
|              !                                |
|              !                                |
| 16 in.       !                                |

I recomend a heat gun for bending. Take plenty of
time and have fun.

Building an aquarium (How to)

Date: 13 May 94
Newsgroup: rec.aquaria

In article <>, (NATHAN R EIDE) writes:
> On this subject, what thickness would you need to build an acriliyc (spelling)
> tank - and where do you find the plexiglass?  Not the same stuff you
> buy at a hardware store - is it?
 Thickness will depend on the volume of aquarium you expect to build, if you
look at the "factory built" units you will notice that they are mostly 1/4" or 
3/8" thick. You can find Acrylic, trade name plexiglass (Rohm & Haas) at any
plastic supply outlet. It is the same stuff you can find at a hardware store,
but I would guess at twice the cost. You also do not have much of a selection
in the hardware stores, if you want to do a professional looking job, you will
need a long length of acrylic so you can "wrap" the front corners. For the
aquarium I built, I had to special order a 12' length of 3/8". You can get any
size you require, up to 20' ($$$) but most distributers don't stock any much
over the usual 4 x 8' sheets. If you wrap the corners you will need to put
together a strip heater to heat and bend the acrylic, the same supply house
should have these in stock. There is a technique for bending acrylic that you
will need to master first (you wouldnt want to destroy $200 worth of acrylic)
once the bend is made, there is no going back, as the heated area has been
distorted, and will always be visable. You need to mark each edge where the
bend will be and line this up on the strip heater. The acrylic should be about
1/4" above the heater, dont let it touch or it will melt the surface and "mark
off" on the acrylic (very ugly). I run a 4' length of 2x4 through a dado on the
table saw to make trough that the heater sits in. Space the other end of the
acrylic sheet with another 2x4 to make it level. Let the first side heat for
about five minutes and flip the panel over. This is *important*, you must flip
the panel over and heat the opposing side to get a clean bend, and you must not
leave any one side on the heater too long. If you do bubbles will form in the
heated area as the acrylic out gasses as it breaks down.(very ugly again) After
10 minutes or so, you will feel the short end of your panel getting "loose",
support it with one hand, and wiggle it to judge how the heating is
progressing. Keep wiggling and bending further and further until you feel that
it will make a 90 degree bend with no effort or "fighting back". At this time
pull the sheet from the heater and make the 90 degree bend. I built a 90 degree
fixture that I could hold the panel against while it cools, it takes about five
minutes before it sets. Tip: make sure that the bend that will become the
outside of you aquarium is the last to see the heater, the outside bend has
farther to travel on the radius and should be the hottest. Use a thickened
acrylic adhesive, not the capillary cement. practice your bends with scrap and
practice your glue up (too much glue looks very ugly also) too little leaves
voids and possible leaks. You won't be able to get those nice 2" radius bends
you see on the better aquariums because the manufacturer builds custom heaters
that are 2" wide, the only heaters available to us are 3/4" (though you could
layout two and get a 1 1/2" bend. I havent tried this though).
Practice, practice, practice...get the technique, its not too hard to learn,
and you will have a beautifull aquarium you built yourself.

Aquarium Photography - tips from

by (Dave Chaloux)
Date: 24 Mar 1995
Newsgroup: sci.aquaria

In article <3ksndm$>, (Chuck) writes:
|> From: (David Jacobson)
|> Finally, you should take along a microfiber cloth (or maybe a small
|> bottle of Windex and some Kleenex if you don't mind attracting
|> attention) and clean the window where you are going to be shooting.
|> You said the aquarium will not yet have opened, so maybe it won't be a
|> problem, but normally, the windows are covered with hand prints
|> and kids' nose grease.

Just don't use windex on any plexiglass our you will have just messed
it up royally (it will glaze).

[M] Three-spot Damsel Spawning

by (Dustin Lee Laurence)
Date: 11 Feb 1993
Newsgroup: rec.aquaria (Brian Hunter) writes:

>In article <> (daniel.a.parker) writes:

The manufacturers hand out sheets on the finer points of handling and
machining acrylic.  I've seen them at a real plastics place (as opposed
to a hardware store that happens to sell acrylic) for free.  If you
can't find a store that has them, you might try contacting a
manufacturer directly.

>Very carefully, I have found water cooling while drilling helps.  You
>also need a specially ground bit.

You need neither if you can locate a drill press.  Keeping the bit
absolutely steady has been the most important thing in my experience.
In particular, as the bit drills out the last millimeter or so it
seems to try to "break through", catch in the acrylic, and try to
jerk the piece around.  If it does this, it will almost certainly crack
the acrylic.  Best is a drill press and clamp; if you don't have the
equipment, you should try to come as close as possible.

You should also drill a small guide hole before drilling with a larger
bit unless the hole you want is tiny.  I drilled a trickle-filter drip
plate with 120 counter-sunk holes using wood bits with no problems at all
(other than boredom after the first few dozen holes).

Finally, it seems that the ultra-sharp premium-quality bits are actually
more prone to catching and jerking than lesser and duller bits.  On the
other hand, if the bit is too dull it will melt the acrylic rather than
drilling it.  A nearly but not quite sharp-as-new bit is probably best if
you use wood bits.

Dustin                         "I contradict myself?  Very well, I contradict
                           myself.  I am vast; I contain multitudes."

Date: 22 May 92 15:00:16 GMT

Transmission of glass vs acrlyic


Measured light transmission of standard soda-lime glass (typical
window/aquarium glass) and poly(methylmethacrylate) acrylic -
"Plexiglass" brand.

Wavelength (nm)                % transmission
                        Glass                  acrylic

600                     90                      90
500                     92                      90
400                     93                      89
375                     90                      69
350                     78                       9
325                     20                       0
300                      0                       0

The thickness of the glass was 3 mm (glass thickness is metric in Canada)
The thickness of the acrylic was 1/8 " (ca 3 mm).

Borosilicate glass (pyrex) is transparent well out into the UV (at least
to 300 nm) but I don't know if it is available in sheets at a reasonable

Different types or brands of "acrylic" may be different.

Kirk Marat
Dept of Chemistry
U of Manitoba

From: (Miller Douglas W.)
Date: 3 May 1994 17:52:46 GMT

Acrylic Maint.


  I've just received some booklets published by the manufacture
of plexiglass (acrylic).  Some time ago there was a discussion on
how to remove scratches for acrylic tanks, I thought I would relay
what they had to say.
<Random comma generator on>

  Before sanding, buffing, or polishing clean the plexiglass carefully.
Small scratches can be hand polished using a soft flannel cloth a good 
grade of automotive paste wax.  Deeper scratches can be sanded,however, 
this will cause a variation in thickness which results in optical
  If a buffing machine is used it should operate at 3000 to 4,500 surface
feet per minute(SMPM). (1/4 buffing wheel diameter in inches multiplied by
the spindal RPM).  The buffing wheels must be clean before starting 
(preferably new).  If an abrasive compound is used to remove scratches a 
different wheel should be used for the final buffing as some of the 
abrasives will remain in wheel even after cleaning.  If the part has been 
deeply scratched or sanded an abrasive coated wheel is used first.  The 
abrasive is a standard polishing compound composed of very fine alumina
or similar abrasive and tallow.
  The plexiglass sheet is next brought to a high polish by a soft, loose 
buff with no abrasive or tallow is used.  These cleaning buffs should 
be very loose and should be made of imitation chamois or cotton flannel.  
The wheel should be 10 to 12 inches in diameter and run at 3,000 to 4,500 
SFPM.  A hand-applied coat of wax may be used in place of buffing on the 
finish wheel, if desired. 

  If sanding is needed first try 600 grit sandpaper wrapped around a 
rubber-padded sanding block.  Sand over the scratch covering an increasingly 
larger areas.  If this does not readily remove the scratch step down to
400 grit sandpaper.  Sanding should be done in directions mutually 
30 degrees apart, producing a diamond pattern.  If 600 grit is used, step 
back upto 400 grit once the scratch is removed.
  Mechanical sanders should be avoided, since the heat generated can cause
distortions and possible discoloring.  Do not use belt or disk sanders, 
if a mechanical sander is used it should be water or better yet oil cooled.
Once sanding is completed buff the sanded area. 

  I personally can not attest to the effectiveness of these methods and
recomned trying the methods, and buffing compounds/sandpaper grits on a
piece of scrap before fixing a scratch on an expensive tank.  Booklets on 
acrylic fabrication, forming, and painting are published by:

Technical assistance phone (215) 785-8290

AtoHaas north America Inc.
Independence Mall West
Philadelphia, PA 19105

AtoHaas Canada Inc.
2 Manse Road
West Hill, Ontario
Canada M1E 3TP

PS I'm currious if you have an acrylic tank, what size is it and what
did it cost you?  I'm thinking of buying or building myself one,
depending on cost and I was wandering what was popular (looks good) 
and the dollar amount involved. E-mail me at
I'll be hear untill the 13Th. (hum... graduating on friday the thirteenth)

Doug Miller  If I don't get the chance to post again thanks for I of the
great info and answering my dumb questions.

Scratches on Acrylic: Help.

Date: 2 Apr 95
Newsgroup: rec.aquaria

In article <3lfls3$>, (Kristi Bittner) writes:
> : For the inside, if you don't want to remove the water nor the fish, you can use
> : a kit called Surface Restoral Kit made by Micro-Surface finishing products Inc.
> : They have some fine wet/dry sand paper called Micromesh.  I have yet to try my
> : kit but my 55g acrylic is badly scratched by my big dogface puffer.
> : I believe the above-mentioned kit is the only tool you can use to remove inside
> : scratches without draining water.  Correct me if I am wrong.
> : BTW, I will use the kit on a marine water tank......
> I've never heard of this before... let us know how well it works, pleeze!!
> thanks in advance,
> Kristi

Okay, I finally used the product Micro-mesh (or Acrylic Aquarium Restoral Kit)
to polish out nearly 95% of all the inside scratches of my 55g acrylic without
draining a drop of water nor take out any marine fish.  It is kinda
time-consuming at first (at coarser grade micro-mesh paper) but as it goes on,
its much easier for the finer grade polishing.

The water will be very cloudy but the guys at Tenecor told me that these loose
particles are inert to fish.  The instruction of the kit does suggest removal
of fish before polishing though.  Anyway, I changed like 40% of the water
afterwards and my fish are still doing excellent now.  If my fish show any
signs of discomfort, I will post to warn others ASAP.

I bought this kit from Tenecor for $34 and the exact same thing runs for only
$24 at TFP!!  I believe you can use very fine wet/dry sandpaper to substitute
for these micro-mesh.  This kit is only enough to polish one face of a show

I could not believe that it is possible to polish out inside scratches without
draining water so perfect.  It is now like a brand new tank.  The scratches I
had before polishing were from:  1. Fine sand being trapped between algae
scrubber and acrylic glass.  2. Decorative corals falling onto the acrylic  3. 
My hugh puffer keep scratching with his beak.  


Melting away acrylic scratches.

by (Chris Paris)
Date: 11 May 1995
Newsgroup: rec.aquaria,sci.aquaria

In article <> writes:
> In the trade this is usually called "Flame polishing", and yes, it has been

I've been experimenting with flame polishing the edge of acrylic
(1/4") using a small butane "pencil" torch. I don't see any
discoloration of the acrylic which you indicated is a problem with
oxy-acetylene flames. If I get it too hot, I get the bubbles you
described. If I don't get it hot enough, no polishing happens (of
course). In between those extremes, I get polishing, but the edges of
the edge (the corners) become proud of the face of the sheet. Here's
an approximate picture, with the effect exaggerated.

   _____         _---_
   |   |        /|   |\
   |   |   =>    |   |
   |   |         |   |
   |   |         |   |
   |   |         |   |

Oops, that picture's terrible. I hope you know what I'm talking about
though. Another problem, which you can see in the picture, is that the
edge, which was flat (though rough) before the polishing, became
curved. Thus, flame polishing (using my bad technique anyway) isn't
suitable for preparing the edges of acrylic for butt joining. I find
sanding to be more successful, though annoyingly tedious. The edge
left by a spiral bit in a router is good enough, but doesn't make as
perfect a joint as if I sand. (I'm doing my cementing with methylene
chloride applied by the capillary action method, through a little

Please advise. :-)

Chris Paris <>    Support censorship -- go to CMU
For information see

Need info on DIY acrilic tanks

by you@somehost.somedomain (Your Name Here)
Date: 29 Jun 1995
Newsgroup: sci.aquaria,alt.aquaria,rec.aquaria

In article <3ssiks$>, Jason Madison <> says:
>Sorry about wasting bandwidth, as this is a repost, but I keep forgeting 
>to put a subject down, so I bet most people ignored my earlier post 
>(with good reason).
>I have been thinking about building my own acrilic tank.  I looked in
>the FAQ, but couldn't find much info on building acrilic tanks (only
>wooden).  Is there a special grade of acrilic that must be used for
>aquariums?  I went to the hardware store and found 1/4 " acrilic that
>looks extremely clear, and I could buy enough for a 4x2x2 with only
>$100.  Can anyone tell me how thick the acrilic needs to be (I know its 
>stronger than glass), and how to seal it.  I know you use a solvent 
>sealer, but do you need a special kind for aquariums or can I get it at 
>the hardware store with the acrilic?  If its as simple as it seems, why 
>havn't I heard more about doing it?
>As always, any info at all would be appreciated.
>Jason Madison

	I would consider trying to get 3/8", unless its lexan.  Lexan is 
much stronger than plexiglass, unbreakable, and about 3 times? the p[rice
I know that
1/2" glass would be needed for a 24" high tank.  I don't have any figures on
plexiglass in front of me, but if you know that plexiglass is <30% stronger
than the glass then 1/4" would be fine.  Also, it would be unwise to make it 
square.  the weakest points will be at the seams.  You can eliminate corners
(weakpoints) altogether by bending the solid piece of plexiglass at the corners.
This will require the correct tools.  I think they're called strip 
heaters/benders (basicaly a 4" by 3' hot pad to heat a section of plexiglass
to a mallable temperature).  Then you can overlap the back seams by about 1".
I was planning on building several until I got the bugs worked out, then 
******* the plans.  But I won't be in a position to do that until the end
of this year.  Use the regular plexiglass glue stuff, but go over all the
seems with silicone to ensure the watertightness.   Hope I have helped.


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