Potassium warning on rotalabutterfly

[*Ci*]

I was in the process of making a stock solution with no nitrate, just K2PO4 and K2SO4.
Using rotalabutterfly, it gave me this warning (which I never noticed before) -

WARNING: The solubility of K at room temperature is 120. You should adjust your dose.
What does this mean, and how does one adjust their dose, please? (or does it not matter much?)

 

[Naturescapes_Rocco]

All dry fert salts have a maximum solubility in water, at room temperature. If you add too much salt per unit of liquid, it won't ever dissolve properly in the solution.

I believe that the "annoyingly missing unit of measurement" on Rotala Butterfly is grams per liter. It's saying that K is no longer soluble in concentrations above 120 g/L. You are trying to add ~170g/L, so about 50g will never dissolve at room temperature. Rotala Butterfly will also give this warning "in advance", so you will also receive this warning starting at 100+g/L, just to be on the safe side.

If you increase your actual dose amount from 40mL to, say, 80mL, you can then just add a larger dose of this liquid fert to the aquarium (to get around the issue of salt solubility):

 

[*Ci*]

Thanks, @Naturescapes_Rocco, I understand (I think).

 

[Burr740]

You can just dry dose K for the whole week right after a water change. To get 10 ppm in solution will require very big doses, as @Naturescapes_Rocco just illustrated. KCL will dissolve a little better but not a whole lot

You can do PO4 the same way. Or make a solution for PO4 and maybe have 2-3 ppm K along with it. Then dry-dose the rest of your desired weekly total for K right after the wc

Personally Id just dry dose both all at once after the wc. A lot of people 'front load' macros that way anyway, esp doing big water changes like 75-80%+, where anything less creates too big of a nutrient drop

 

[*Ci*]

I normally dry dose my macros once a week after the water change, but I switched to stock solutions because it seemed like so much work to haul out all the jars and spoons, and measure each one into a bottle to shake up. I do baking soda, calcium chloride, epsom, kno3, k2so4, kh2po4, micros and SAFE)

With the stock solutions, I put them into these bottles and just squeeze and pour. With 4 tanks to do on W/C day, it actually saves a lot of time!
The bottles dose up to 50ml per squeeze, so 2 squeezes to get the 80 ml I need, and I’ll probably make up 4 litres of stock. I’ll try it anyway, and I could always go back to dry dosing.

Thanks for the advice @Burr740 .

 

[Kwyet]

Cool idea!

 

[Koan]

The bottles dose up to 50ml per squeeze

Where'd you get the cool bottles?

 

[*Ci*]

Where'd you get the cool bottles?

Amazon …

Adjustable Volume Dispensing Bottles

 

[Burr740]

I normally dry dose my macros once a week after the water change, but I switched to stock solutions because it seemed like so much work to haul out all the jars and spoons, and measure each one into a bottle to shake up. I do baking soda, calcium chloride, epsom, kno3, k2so4, kh2po4, micros and SAFE)

With the stock solutions, I put them into these bottles and just squeeze and pour. With 4 tanks to do on W/C day, it actually saves a lot of time!
The bottles dose up to 50ml per squeeze, so 2 squeezes to get the 80 ml I need, and I’ll probably make up 4 litres of stock. I’ll try it anyway, and I could always go back to dry dosing.

Thanks for the advice @Burr740 .

Ahh I gotcha. I just wanted to point out that its fine to front load all the K in case you didnt know

Fwiw you really dont have to pre-dissolve it before adding it to the tank. Dry salts straight from the tsp directly in the water is fine. If any lands directly on some leaves you can just reach in there and gently fan it off.

But thats a lot of compounds you have there! Looks like a good system you have going, I get it