as this site seems helpful got another query i`ve now got a large pond filter for my tropical pond i also got a a nice size plastic overflow tank with it which the guy used for his pump to return the water back to his pond.(this came along at such a cheap price couldn`t resist saves me makeing one)

The thing i would like to do is use this as the feed to my heater on the return leg and a smaller bore pipe for my coil denitrator the actual filter will be pump fed at 200 litres a min at a head of approx 1 metre .

The size of the header tank is 66cm long 55cm wide and 43cm high approx 150 litres the return pipe will be 2 1.5 inch pipe + 1 20mm pipe for denitrator one 1.5 inch pipe will have a valve on so that i can regulate flow to heater .

I was going to put the pipe about 40mm from top of tank will this be enough for gravity to feed heater and denitrator please?just trying to do it so that i only have to run 1 pump

or would it be better with pipes at bottom and how much of a difference between fall and rise would i need please?

First what sort of heater are you going to use as different heater's have different flow rates.
If you are using a bottom drain then the heater can be used after the filter as this is pumped back to the pond, if however you are using a pump fed system the heater should go before the filter!
This of course is subject to what type of heater you are using.
(the above is based on an inline heater!!)

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