KH

[Duncan]

some folks have emailed me lately about how much bicarbonate of soda to put in a pond to raise the pH

well the true answer is there is not definitive answer to that because 500 gm of bicarb in one pond will raise the pH one way and in a different pond it will raise the pH another and there are several things that influence pH
BUT: and its a big but, I can tell you how much bicarb to put in to raise the KH in as pond and that's probably more important as this directly effects the alkalinity and therefore will in some way raise the pH

so pro-rata 70 gm of bicarb in 500 uk gallons or 2273 litres will raise the KH 18ppm or 1 GDH from there you can work out your pond..
140gm to 1000 gallons or 4546 litres works out the same =18ppm or 1 degree

if you want the maths I can give it but you only need this

dunc