Question about ferts

[isu712]

I have a newly assembled planted tank. I've only had the plants in there for a couple of days, but I have a question about ferts. How do people tell how much potassium is in their tank? I haven't been able to find a test kit. Should I just assume there is none in there? I'm going to start dosing with Seachem's Nitrogen, Phosphorous and Comprehensive. I'm assuming I'll need Potassium but I want to know if there's some way to tell if I need it or not. Here's my tank specs so you can become more familiar:

Volume: 20 gal high
Light: 2x24 watt T5HO
CO2: Store-bought DIY yeast system

If you need anything more let me know.

 

[Zezmo]

You do need potassium.

Often, even if other ferts are not added, that one is still required.

 

[travis simonson]

Potassium is necessary and fairly hard to overdose. Minimum K levels in a heavily planted tank should be around 2 ppm with 20 ppm being the upper limit. There are no affordable and reliable K tests out there so I simply dose about 15 ppm (in ~4 ppm increments dosed every other day) each week. If I notice any pinhole damage in older leaves or thin/transparent leaves, I increase the dosage. It has worked quite well for me.

 

[isu712]

Thanks travis, that's exactly what I needed. The leaves on some of the plants seem like they are becoming kind of "transparent." It sounds like I need to add K. I'll give it a try.