potassium questions

[plah831]

Potassium supplements are expensive! How do I test for K levels so I know if I need to supplement? I've seen in the stickies recommendations for cheaper alternatives. Are those sources still good? If I use a table salt substitute, is the extra chloride ion harmful? Where does it go?

 

[Goatman]

I have been told that Cl- inhibits N uptake. You can use KNO3 (stump remover) if the little added CL- is a concern. I've been using KCl for a couple months with no ill effects.

 

[reiverix]

Potassium sulfate (K2SO4) is cheap from http://www.gregwatson.com/.

K isn't something we can test for except if you have access to a lab, but it's not something easily overdosed unless you go silly with it. Pinholes on leaves are a sign of a deficiency.

Goatman, there's a few of us have been experimenting with Cl (usually with CaCl2 for calcium) and we have had better results keeping the chloride out of the water column. I now use CaSO4 for calcium.

 

[djlen]

Most of the substitutes for nutrients are just as good to use. In fact, I use Fleets Enema exclusively for dosing P because I find it easier and more precise to use than the powdered form commercially available. Also, Epsom Salts for Mg is readily available at the pharmacy so I use that.
Years ago, I switched from stump remover to the more pure version of KNO3 available from Greg Watson, but certain stump removers are OK to use.

Len

 

[wesleydnunder]

Len, since you use fleet, how do you dose? I also use fleet but I'm not confident in my phosphate test kit so I can't accurately gauge what ppm I'm adding. I have a 125g tank and add 6 drops 3 times a week. Whats the correct dosing? I also use KCl for potassium.

Mark

 

[Bmeasure]

Len, since you use fleet, how do you dose? I also use fleet but I'm not confident in my phosphate test kit so I can't accurately gauge what ppm I'm adding. I have a 125g tank and add 6 drops 3 times a week. Whats the correct dosing? I also use KCl for potassium.

Mark

I had the same issue using enema products for a while, until someone finally helped me out. I was having very steady algae problems for over a year, and I was starting to doubt my test kit because I was dosing up to 20 drops on a 150 gallon tank. I was nervous that the algae was coming from me overdosing my tank with PO4. The opposite was actually true! I finally had someone tell me the amount of drops to add........82 DROPS!!! I believe I was going for about 1ppm (it may have been 2ppm though). Either way, when I started adding these huge doses, I started having a much easier time with the algae. The tank still didn't work out as a planted tank because the cichlid would tear my plants to pieces, but the Phosphate problem was solved!

For your tank I would try about 60 drops of Enema, and then test and go from there. You can later add 30-40 (or more) mid-week depending on the plant uptake, but you'll have to figure that out for yourself. Sometimes LESS ISN'T MORE!!!

I think I kept dosing so little and doubting my test kits because the suggestions for fert doses are so generalized in most posts. I'd hear things like, add 1/2 tsp KNO3, 1/4 tsp of K, 3 caps of Flourish, and 3 or 4 drops of Enema. Most people don't think about HUGE planted tanks when giving advice. By the way, I use Seachem Phosphate tests, personally. They seem most reliable to me.

 

[wesleydnunder]

Thanks, Bmeasure. I'll give that a try.

Mark