Do I Really Need A Polystyrene Support Layer?

BFG · Jul 4, 2006

Hi,

I won the tank linked below. It's about 60 litre, and is glass. It's got a black plastic base (thus my reason for asking). It will be put on a stable level wooden surface, but won't be a purpose built stand. The inside of the plastic tray seems to have supports within it that meet the glass at various points.

http

/cgi.ebay.co.uk/ws/eBayISAPI.dll?Vie...item=7774353310

What do you reckon? To polystyrene, or not polystyrene, that is the question!

Thanks,

BFG

Tolak · Jul 4, 2006

If the tank rests on the rim, and not flat on the bottom no padding is needed. The weight is carried by the rim. To check, flip the tank over & put a straight edge across to see if there is space.

Put the straight edge acroos the table you plan to use in a few different spots to see if it is level. Also, once the tank is in place, take something like a matchbook cover and go around the perimeter of the base to check for any gaps. Anything more than an inch or so means the surface isn't level.

Rooster · Jul 8, 2006

BFG said:
What do you reckon? To polystyrene, or not polystyrene, that is the question!

Thanks,

BFG

YES YES YES !

I have known of several tanks burst for no apparant reason... some hours after filling, some years - glass is NOT a solid, as most people assume... it does flow, but at a VERY slow rate... the load will shift over time, and if there is NO flexable support it WILL fail :no:

Tolak · Jul 9, 2006

This has to do with the tank design, not the liquid properties of glass. Some tanks are designed to be supported by the rim ONLY. Putting padding under these type of tanks risks having the padding placing pressure on the sheet of glass on the bottom, a pressure the tank was not designed to handle. This will cause anything from seam leaks to catastrophic failure.

Other tanks are designed to have the entire bottom bear the weight, these do need some sort of padding, any small uneveness of the stand, or a small particle of something hard between the tank bottom & stand will cause a huge amount of pressure in that area. This will cause the same problems as putting padding under a tank that wasn't designed for it.

I'm glad you brought up the properties of glass flowing. I have an old tank, built in the late '40s to early '50s. I also have a micrometer at work. If the liquid properties of glass affect aquariums, there should be a consistent measurable difference in the glass of that tank top to bottom, just as there is in 100 year old glass windows. Sounds like another thing for me to play with.

BFG · Jul 9, 2006

Cheers for the replies. Tank is now set up - looked into this a bit further and the plastic base that came with the tank seems to be for weight distribution etc (it's supporting the rim) (cheers for the pointer Tolak).

It's not the biggest tank in the world, and I'm only using it temporarily as a quarantine tank, so hopefully even if it's not perfect it'll be taken down in 3 or 4 weeks.