Fixing 2 x bilge pumps to bottom of loft tank

[bowlingo]

Hi all,

I am working on a project and need to screw 2 x large bilge pumps to the bottom of a 25 gallon plastic loft tank...here is the tank

POLYTANK 25 GALLON (114 LITRE) COLD WATER STORAGE TANK (27&q...

At the moment I have stuck a piece of plywood to the bottom of the tank using gorilla glue and screwed the bilge pumps onto it using 12mm long fat wood screws.... but its only a question of time before the plywood comes apart and the bilge pumps fall over.

I am thinking of say a 15 - 20mm plastic sheet of which I will glue onto the bottom of the tank using a 2 part adhesive mix..

Ive just bought some of this

Bondloc UK - manufacturer of Industrial Adhesives and Sealants

The plastic that I stick to the bottom of the tank and screw the pumps to would have to be of such a density that when I screw into it it would grip the screws tightly like the ply im currently using does.

Does anyone have any ideas on a better way or where to get a sheet of suitable plastic thats 500mm x 400mm x 20mm ?

Thanks
Alex
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[stevetheplumber]

Ive fitted a few pumps in tanks usually as sump pumps for various things trouble with fixing them down is geting them out again for maintenance
weve always piped then rigid with unions to allow removal or droped them down on a cable/chain and wieghted down with weights hanging just clear of the bottom might help if you say what these are to be used for

 

[bowlingo]

Hi Steve..

Its for an automated Hydroponics system thats controlled by SMS (mobile phone)...im into electronics and an electrician by trade. Ive pretty much built it now and am looking to iron out a few things..one of the bilge pumps is for emptying/flushing the tank and the other is for mixing the 100 litres of water/nutrients. The one that mixes is this one..

Portable Water Pump - Watering - Gardens - Wickes

and the one that empties is this one..

JOHNSON Bilge Pump 12v L450 778GPH Submersible | eBay

The one that mixes ive had to screw 4 x L brackets onto the bottom of it so it can be fixed down

The one that empties already has screw fixing holes on the bottom

The little one that empties empties the 100 litres in 4.5 minutes and the one that mixes swirls the water round like a whirl pool for 3 minutes both on command by text message.

I cant hang the pumps into the tank so I need to somehow fix them to the bottom of it..hence the 500 x 400 x 20 piece of plastic glued down idea with screws holding the pumps to the plastic.

As for getting them out for maintenance theres enough room to unscrew them after emptying the tank either by using the small drain pump, using a drain valve ive fitted or by using buckets

Thanks

 

[justlead1]

Hi. Just cast your self a slab of lead and screw the pump to it. The weight will hold it in place and can be lifted out should the need arise.

 

[bowlingo]

I thought about fitting something heavy to the bottom of the pumps (didnt think of lead mind you) trouble is lead is expensive and im pretty sure the lead would poison the plants (nutrient solutions in tank)

Anyone any ideas on where i can buy some high density plastic 500 x 400 x 20 thats going to grip some 15mm fat screws nicely?

 

[Resolute]

Can you not just glue the pumps to the bottom of the tank?

 

[bowlingo]

I wont be able to get them out again should i need to if i do that

 

[stevetheplumber]

ive got a bigger version of those in my fish pond and it just sits there or i hang it on string if i want to skim the top
the bilge pump has fixings as its designed for use in a moving boat think your over complicating the task especialy as its not for drinking water
just stand them in if they move at all just wieght them down both pumps draw in from the side rather than bottom so no need to raise them
any wood will break up in no time especialy man made boards

 

[bowlingo]

The mixing pump uses its out funnel to mix the water of which is like a whirlpool..if its not fixed it will move all over the place...I have expensive probes in the tank that I dont want it to hit. Also because its left unattended if the water level is low it could splurt water all over the place..the main big mixing pump dosent have fixings as ive had to fix L brackets to it