Help needed for new dosing routine.

Staff member
Sep 13, 2008
Laguna Niguel, CA
Hello everyone, I need advice for a new dosing routine that could better fit my water change schedule which is currently based on a 50% water change every 2 weeks. Unfortunately I can’t currently afford to change water more often than that.

I have easily found out the amount of macros I need to dose every week without accumulating them too much (just because I can easily test KNo3 as well as Po4), but I am having issues to calculate correctly the amount of micros, that I’d like to be able to dose as a solution daily for the sake of simplicity, and I want to be sure to avoid possible deficiencies as well as possible accumulation of traces which could potentially take me into the toxicity realm as I have read around (with the every-two-weeks water change schedule, accumulation of nutrients is something that could more easily happen than with the traditional weekly water change routine).

Here is my current tank’s data:

75gl tank with wet/dry filter

Pressurized Co2 30-40ppm during photoperiod

Photoperiod of 7 hours a day.

Light intensity: 40-50 PAR at substrate

KNo3 weekly dosing: 3 x 1/4 tsp (about 4.24 grams)

Po4 weekly dosing: 1 x 1/8 tsp (about 0.50 grams)

Tank is heavily planted, see a picture of my tank at the link below to understand my plant density:

The schedule I’d like to have is the following, based on a 2-weeks schedule with water change on Saturday:

1st week Saturday: 50% WC + macros dosing

1st week Sunday: traces dosing

1st week Monday: traces dosing

1st week Tuesday: traces dosing

1st week Wednesday: traces dosing

1st week Thursday: traces dosing

1st week Friday: traces dosing

2nd week Saturday: macros dosing

2nd week Sunday: traces dosing

2nd week Monday: traces dosing

2nd week Tuesday: traces dosing

2nd week Wednesday: traces dosing

2nd week Thursday: traces dosing

2nd week Friday: traces dosing

I’d like to dose micros by using 1 liter solution that I can dose daily from Sunday to Friday, and I found that a possible dosing regime would be making a solution of 1 liter (1000 ml) with about 40 grams of Plantex CSM + B which would give me a daily dosing of 10 ml. By using Wet’s calculator, looks like that that will give me about 0.1 ppm of Fe a day… will that be enough? Or will that be potential of accumulation issues in the future? I have used the very cool “Accumulation of fertilizers vs time and plant uptake” from Wet’s calculator, trying to understand what are my risks, but it is very difficult to have useful data without knowing my tank’s plant intake… how would you know that? From the picture of my tank and my tank’s data above, how much intake would you think my plants would have every week? Do you think such a kind of trace regime would be sufficient, not enough, or too much?

I am open to your advice, thoughts and suggestions… thank you to all in advance!



PS: I am afraid to have found a bug in Wet’s calculator, if you try to calculate the dosing of Plantex CSM+B for “EI daily” and “EI low light/weekly”, how is it possible you get the exact same result???