The chamber had 2 “letter box” style outlet transfer ports.

These two upper, outlet “letter box” transfer ports were converted to 2 “centralised” 4” strainer outlets, and the following article details how this was achieved.

2 X 316 stainless steel conversion plates to fit over the existing transfer ports were custom fabricated by a specialist for me.

These were fixed in place using stainless steel bolts and sealed with silicone sealant.

Special 4” tank connectors (from East Riding Koi) were used to facilitate the connection of 4” pipe to the conversion plates.

All pipe work connections were glued.

The 2 conversion plates and the 4” tank connectors were fixed in place.

4” pipe could now be glued into these, to which would be fixed the 2 stainless steel mesh (5mm) strainers.

This is of one of the 2, 300 mm long, stainless steel strainers (5mm) prior to it being fixed to the 4” transfer pipe work with a couple of stainless steel self tapping screws.

Note that one end is open and the other closed.

Here is the final conversion. You can see the modified transfer pipe work (black) and the 2 stainless steel strainers which feed the next chamber.

Note. Depending upon the situation, a small air-bleed hole/ tube may be needed at the top of each of the 90 degree elbows in order to prevent air locks.

The perforated sheet was been left in place as this will prevent any K1 being lost when the chamber's bottom drain is opened (a strainer could have been fitted over the drain as an alternative).

The 12 mm compressed air “Speedfit” fittings used for the air ring are made by John Guest, and can be obtained from a specialist supplier. They have the advantage that they are push–fit and can be easily disconnected too.
The 12mm airline is made of Nylon and is quite stiff, but sufficiently flexible, and can be easily cut with a utility knife.

Here is the finished conversion, and the chamber filled with 200 litres (4 X 50 litre bags) of “semi-mature” Kaldnes K1.
The K1 here was helped to “mature” by placing it in mesh filter media bags (available from many Koi dealers) and floated in the other chambers of the filter. This would help give it a bit of a kick start, and was done 6 weeks prior to the conversion.
The 200 litres of K1 is adequately “fluidised” here with 40 litres/ min of air.

Note: New K1, straight out of the bag, will float for several days, before becoming semi-buoyant and fluidising / rolling correctly.

The overflow pipe work (seen temporarily capped off on the left) was subsequently removed and sealed off, as it was not required. If it had been left in place a strainer would have had to have been fitted to prevent loss of K1

So, how much K1 do you use for a given size chamber?
The ratio of the volume of K1 in relation to the chamber volume is quite important. You need to calculate the volume of your chamber in litres. To calculate the volume of your chamber in square inches multiply the length by the breadth by the depth (L x B x D). Then multiply by 0.0164 to give the number of litres. Centimeters are easier, simply divide total volume by 1000 to give litres.
It is possible to use no less than 30% to a maximum of 67% of this volume with K1. An average of 50% is recommended.

Examples:
1. Tank 24" x 24" x 24" = 13,824 square inches.
Multiply by 0.0164 to give 227 litres volume of the chamber. Then multiply this by 50% to give 113.5 litres of media (recommended).

2. For a 24" vortex with a straight side 24" depth to the cone of this would be 12 (half its diameter) x 12 x 3.14 (pi) x 24 (height) = 10,581 square inches. 10,581sq" x 0.0164 = 178 litres. = 89 litres of media at 50%