# fert help please



## jrs (Mar 18, 2006)

I am just making up my fert schedule and I am using "Chuck's Planted Aquarium Calculator".

It says that I can use potassium chloride (KCl) as a source for potassium. If I use this I will be adding Cl to the tank as well. Is this right?

jrs


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## holocron (Mar 12, 2006)

yeah, you will. I would recommend KNO3 as a source of potassium and nitrate. K2SO4 is also good for potassium. Have a look at these PMDD links:

http://www.thekrib.com/Plants/Fertilizer/pmdd-tim.html
http://www.aquabotanic.com/PMDDprimer.htm

There are lots of different recipies, I made the ones specified on those pages and now just dose what I need based on the growth and tank parameters.


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## wtac (Mar 17, 2006)

Personally I'd use either K2SO4 or KNO3 as the anions (SO4- and NO3-) are more "useable".


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## Plant Crazy (Mar 24, 2006)

jrs said:


> I am just making up my fert schedule and I am using "Chuck's Planted Aquarium Calculator".
> 
> It says that I can use potassium chloride (KCl) as a source for potassium. If I use this I will be adding Cl to the tank as well. Is this right?
> 
> jrs


As others have suggested, the best approach is to use:

KNO3 (for nitrate)
KH2PO4 (for phosphate)
K2SO4 (for potassium)

This way, you won't be short of potassium, especially given that additional potassium is being provided by the KNO3 and KH2PO4.

As for a dosing regime, I've found that checking my nitrate and phosphate levels (AP brand test kits), and dosing my PMDD (http://www.thekrib.com/Plants/Fertilizer/pmdd-tim.html) daily with phosphate dosed separately works best. I don't bother checking my Fe levels, since I'm adding trace daily (in the PMDD mix already). Also, no need to check potassium levels.

Homegrown hydroponics sells all the ferts separately, for very reasonable prices.

By mixing your custom PMDD mixes(e.g., PMDD without nitrate, PMDD with triple the dose of nitrate, etc), and a separate phosphate solution, you can dose the amount of nitrate and phosphate that you need. I aim to keep the nitrate level between 5-10 ppm, and phosphate between 1-1.5 ppm.

There is an 'Estimative Index' (EI) that has been advocated by Tom Barr: http://www.barrreport.com/forums/showthread.php?t=1 . It's a very simple method that doses macros and micros on alternate days, and employs a massive weekly water change (which essentially 'resets' the levels of macros and micros on a weekly basis). This method also claims not to need test kits. I haven't tried the EI technique, since I like knowing the levels of my nitrate and phosphate, and dose based on this. However, the EI system is widely used and straightforward. Note, regardless of what method you choose, dosing on a daily basis seems to work best.


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