Question about dosing

[Liz]

I do not understand how the example dosing above is derived from the recommended range for nutrients and the size of the tank. I used Chuck's teaspoon to gram equivalents (5.6 for KNO3 and 5.8 for KH2PO4) and calculated that every other day this scheme adds 0.86g NO3, 0.26g PO4 and .65g K to 80L of water. If I did the calculation correctly that would be adding to the tank 11ppm NO3, 3.2ppm PO4 and 8.1ppm K four times a week. That would be dosing at the low end of recommended NO3, double the recommended PO4 and a little below the recommended K every other day.

I am trying to figure out how to start dosing my own 55G/210L tank that is lit with 2.5 wpg and has CO2 running at about 25ppm. Should I be shooting for the middle of the recommended range every other day? Also, I have CSM + B dry trace mix. I am guessing that I should dose that to achieve 0.5ppm Fe. (I have a scale available that weighs to 0.01 g.) Thanks for the help.

 

[Tom Barr]

Re: Question about dosing

It's not particularly accurate, nor needs to be within a certain range, it's easy to suggest though. Most are heavy on PO4 and K, this does no damage, perhaps a tiny bit of waste with PO4 dosing. I do not tell folks to add 10ppm of NO3 1.0ppm PO4 etc, it's just easier to suggest it this way, accuracy is not needed since we are adding to excess in each case. More will not hurt. The method is slanted to low NO3, but some comes from fish, K+ relative to plant needs is about 4:1, so you will have about 4.3 X more K than you need if you use KNO3 to dose N. Or 75% of your N can come from fish waste before you need to add K2SO4+KNO3.

I'd suggest this for your tank:

50% water change a week

2-3x a week: 1/2 teaspoon of KNO3

Same for the KH2PO4 except 1/16"- 1/8"

Traces: 10mls 2-3x a week

I add these nutrients back right after the water change.

Add 500mls of water to the trace mix(@ 2 table spoons/500mls)

If you want to use th calculators to get these ppm ranges you are welcomed to. A narrow range(adding just enough) is not robust method and does not take into account different plants species, water conditions in the tap, plant density.

These ranges are on the high side, but there is nothing wrong with this. Main thing is to keep enough CO2/nutrients.

Clean tank top to bottom(always) and prune/preen, clean the tank/filter first, then do the water change. If you prune and keep on this, CO2 etc, you will do very well.


While precise ppm ranges are nice, the reality and the methods folks generally use, allows a great deal more wiggle room.

I've used the ranges I've suggested for many years on all sizes of tanks.

Regards,

Tom

 

[AV8TOR]

Re: Question about dosing

Tom I notice that in your EI you don’t add any Potassium (as above per example). Is this your feeling that all the K the tank needs is being taking care of with the KNO3 dosing?

 

[Tom Barr]

Re: Question about dosing

Yes, ample K+ can be supplied via KNO3 exclusively. Until you get to the point that the outside NO3/NH4 sources are adding roughly 75% of the tank's N demand, then you will be fine. That is very rare in CO2 enriched tanks........Even heavily stocked Discus tanks still use roughly 50% of their N from KNO3 if they are well maintained.

So you have a ratio of about 4K's for each 1 NO3 you add using KNO3 as far as plant use(4:1)

I'll go through K+(and most of the others) pretty well in the coming months.

Regards,

Tom Barr

 

[Liz]

Re: Question about dosing

Okay, I think I have the philosophy behind the recommendation. Thanks

 

[Tom Barr]

Re: Question about dosing

If you have any questions, please do not hesitate to ask. Questions and comments are encouraged here. Often they will be answered in a thorough manner in a particular chapter but sometimes folks cannot wait or have other questions. Sometimes it will tak several back and forth comemnts to get to the bottom of a problem or concept.

Please be patient with your self. I'll keep hammering it till you get it right.

Tom Barr