Thats what Tom said. You can read about why some opt out of using Urea here
where Tobi intoduced is mix originally at UKAPS. This is a quote from Tobi's instructions:
I'm producing ferts commercially (Aqua Rebell and sell them through my shop "Aquasabi") for people who do not want to work with all those chemicals.
But here is the recipe for the new nitrogen fertilizer, i've posted it at my community http://translate.google.de/translate...4.html&act=url
for one liter water add :
25,9 g potassiumnitrate
29,5 g calciumnitrate
17,6 g magnesiumnitrate
5 g urea ( :arrow: your tankwater pH should be <7 to avoid problems with ammonia)
That will add 1 ppm NO3, 0,2 ppm K, 0,1 ppm Ca and 0,033 ppm Mg using 1 ml per 50 l tankwater.
Here is where you can order Tobi's mix
I've read about this about a year ago but I couldn't use urea because my pH is north of 7.0. The mix isn't new and was tried in the past but if Happi "improved" on it a bit then I say have at it. Just be very careful when using Urea. I think the focus is more on getting the nutrients to your plants that they are lacking.
I'm in Texas where the water is basically liquid rock. Now one would think that I have enough calcium and magnesium because my GH and KH are through the roof, most of the times north of 14 sometimes as high as 22. What I discovered was that the water is very rich in calcium but had very little to no magnesium so when I started adding just magnesium the plants perked up and took off.
Just like in the UK, the water is rich in calcium but has very little magnesium in some places so when they started adding magnesium the plants reacted in a very positive way. If your plants are getting the nutrients they need and are none-limiting, no amount of Urea is going to change that. Just be careful and enjoy the plants