Polystyrene question

[Fisher2007]

So I'm in the process of switching over to my new tank. The tank is 1420 long by 410 wide and 450mm tall and it will be sat on an existing oak cabinet I have, which has held a smaller 600 by 450 by 450 tank for the last 4 years. On removing the old tank though I've discovered the top of the cabinet is not perfectly flat to looking for ideas and thoughts

The unit is 1500 long and through the length has a slight bow up in the middle. If I put an 1800 long level on the until there is probably 1-2mm either end of the level with the middle third of the level flat on the unit. Until discovering this I was going to put the tank directly on the unit but now I'm thinking I need to put it on polystyrene and I have some 18mm poly to hand. Will this be enough to account for the imperfection in the top of the unit though? The new tank has a floating base, I think it's called, where the sides go straight to the base of the tank with the base of the tank within the perimeter of the side walls

Just to add, the bow on the stand is not due to damage or water ingress, just simply how it had been constructed. The top of the unit is as good as new
Thanks

 

[Barbara Turner]

Yes, polystyrene should be OK, fill it up slowly and keep an eye on it. Googling eps foam the worst stuff is rated to 20kpa or 0.2kg/cm (142 x 41 x 0.2) =1164kg at 2% compression long term.
250 litres of water +50kg sand /rocks + 50kg tank your still okay

It can be a pain to move the tank afterwards as forms a airtight seal, something like a fleece blanket on top can help.

I would be slightly worried about your oak cabinet though. I would reinforce it, as normally you find the doors don't open. I added extra centre legs to mine and a extra reinforcement. (all hidden)

 

[Fisher2007]

Yes, polystyrene should be OK, fill it up slowly and keep an eye on it. Googling eps foam the worst stuff is rated to 20kpa or 0.2kg/cm (142 x 41 x 0.2) =1164kg at 2% compression long term.
250 litres of water +50kg sand /rocks + 50kg tank your still okay

It can be a pain to move the tank afterwards as forms a airtight seal, something like a fleece blanket on top can help.

I would be slightly worried about your oak cabinet though. I would reinforce it, as normally you find the doors don't open. I added extra centre legs to mine and a extra reinforcement. (all hidden)

Thanks!