help with how many dosing

Fitos

New Member
Joined
18 Feb 2019
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11
Location
Cyprus
hello to everybody.
until now I added liquid fertilizers in my aquarium.
Recently a friend of mine gave me some KH2PO4 to fix a liquid fertilizer by my own.
I got in one of the calculate websites, so I can do the mixture.
on 250 ml of distilled water I added 50 grams to end up with 2ml dose which it will raise the PO4 1ppm.
If I do this by adding 10 grams I will get 10 ml dose and 1ppm PO4
So these two dosages are the same. which one is better to add in the aquarium?
 

dw1305

Expert
Joined
7 Apr 2008
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10,429
Location
nr Bath
Hi all,
on 250 ml of distilled water I added 50 grams to end up with 2ml dose which it will raise the PO4 1ppm.
Yes, it would be better to use a larger volume of water, and only make it up to the final volume after all the KH2PO4 has dissolved. The dissolved salt adds to the volume of the water, so you won't have 250 ml of water, it will be nearer to 300ml by the time the salt has dissolved.

You are also approaching the solubility limit of KH2PO4 (22.6 g/100 mL of H2O at 20 °C).
2ml dose might be easier to measure using a pipette as they only go up to 3ml.
You can always just weigh larger volumes of liquid. Because liquid fertilisers are dilute solutions of water you can use one millilitre = one gram.
So these two dosages are the same. which one is better to add in the aquarium?
They are the same and it doesn't make any difference.
If I do this by adding 10 grams I will get 10 ml dose and 1ppm PO4
I always prefer working with larger weights and volumes, mainly because you can be much less precise with measurement (for example you can use kitchen scales, rather than a scientific balance).

I'm assuming that your tank is about 260 litres? So you've added 1 ppm PO4--- and ~0.4 ppm K.

cheers Darrel
 

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