hi,
read this.....
http://www.ukaps.org/forum/viewtopic.php?f=34&t=1211
100 liters = 25.5 us galls, after substrate/hardscape displacement, you can dose for a 20 us gal tank!
dose this, eg monday, wednesday and friday.....
NPK (Nitrogen+Phosphorus+Potassium) Mixture for 20 Gallon Tank
1...