[gpodio]

I've used Flourish nitrogen in the past, gets expensive though. If you are jumping on the "low K" wagon, then I don't think you will ever have problems if your only source of K is from KNO3 and what little K is in your trace mix. Increasing the fish load would increase nitrogen levels and therefore you would use less KNO3.

Although I have never tried it, NH4+ may be one alternative, if dosed correctly it should be prefered by the plants and removed or converted rather quickly by plants and bacteria. What is converted by bacteria and not consumed by plants would then become nitrate which in turn goes back to the plants should they run out of NH4+.... Although you'd have to dose very small amounts throughout the day to prevent levels becoming toxic to fish. ...works in theory right? ;-)

Urea is another nitrogen source however both of these alternatives could possibly cause some issues with algae growth. I think I'd stick to KNO3 personally. Others might have better alternatives.

Giancarlo Podio

 

[gpodio]

I know of no upper limit on Ca levels, I've been to 440ppm.
As far as K+, I went well above 50ppm recently. Erik said he went to 100ppm K and we both grow Ammannia and funny odd plants etc.
I know the high K+ thing is a bandwagon, but whatever works as long as the K+ is not limiting.

Tom,

I've been following the K+ threads lately but have been reluctant to post any opinions about it. Mostly because the people who are warning us about K levels know a lot more than I do about chemistry so I take their suggestions rather seriously. However last year I spent a lot of time raising and lowering levels of individual elements to see the effects it would have on my tanks. In the month that I played around with potassium, I didn't notice any problems in plant growth when I dosed 20-30ppm each week. I did however have signs of calcium deficiency in my A. Gracilis, before, during and after the potassium tests. I eventually solved it by adding calcium and magnesium tablets in the substrate. My E. Stellata shows signs of calcium deficiency when my Flourish Tabs are all consumed for example, but it's hard to say if it's actually calcium or just a nutrient shortage of some other kind.

Either way however, I have never kept a potassium level of 30ppm as some suggest, I've always dosed around 5ppm following water changes and another 5ppm in the daily doser distributed throughout the week. Other K sources are obviously KNO3 and my trace mix. So I guess I'm somewhere in between the two "bandwagons".

I'd like to test this again for longer than a month, perhaps that will give me different results. Either way, what's your take on this? And what, if it's not potassium "overdose", could be causing such signs of deficiency in peoples tanks when K levels were raised?

Regards
Giancarlo Podio