Dosing macros with Seachem

[zenkatydid]

So after a couple of weeks of sitting in the post office, "lost", I finally have my macro ferts. I have 250ml bottles of Seachem Potassium, Nitrogen, and Phosphorus. My tests show I am at 0ppm NO3 and 0.5ppm PO3. The NO3 has been holding steady at 5ppm over the last few weeks, but has obviously bottomed out in recently, after adding a couple new plants a few days ago.

So, I need to dose about 15ppm N and about 0.5ppm P. I also would like to add 15ppm K. According to this calculator, that means in my 50gal (200l) tank, I need to dose 40ml of Seachem Nitrogen, 20ml Seachem Phosphorus, and a whopping 70ml Seachem Potassium.

Is that correct?! Those are ridiculous and unsustainable amounts. The 250ml bottle of K, for instance, will last a handful of doses. Tell me I'm doing it wrong?

 

[rkilling1]

Those sound about right to me. That is why you hear most of us saying to get dry ferts!

EDIT: I confirmed the K dosing on seachem's website and you are correct with 70ml's 2-3 times a week. I guess you should start ordering more for next week or look into other ferts.

 

[rich311k]

I hate to say this, but yes your figures are probably right. I see you are in Australia so Greg Watson, wont help you much. Maybe other Australian members will pipe in with where they get their ferts from.

There are substitutes. Fleet enema can be used for phosphate. NoSalt (KCL) a salt substitute, can be used for potassium. KNO3 can be found as stump remover in the US.

Hopefully some one from down under will help you out.

 

[Zezmo]

Seachem ferts are very diluted.
In 50 gallons:
8tsp Flourish Nitro=16ppm
4tsp Flourish Phos=.5ppm
14tsp Flourish Pot=18.49ppm

I have made a spreadsheet for my EI dosing, it includes calculations for all the Flourish products.
http://webpages.charter.net/zezmo/EI-DoseRoutine_v4_public.xls

 

[malkore]

Yep, those numbers are right. Seachem is a good product, but not designed for use with high light, CO2 injected systems, particularly larger setups like yours (and mine).

A $7 bottle of their potassium will dose my 75gal tank with 15ppm about 2.3 times before the bottle is empty.

www.gregwatson.com is an option for those of us in the USA. It looks like you're in Sydney, Aus?

try local greenhouses, especially hydroponic stores. a pound of potassium sulfate, potassium nitrate, and a half pound of mono potassium phosphate would last you years, and cost $5 US

 

[zenkatydid]

oh my god. that is insane. i knew dry ferts were better, and lasted longer, but i didn't realise how ridiculous (not to mention expensive! grr!) this way was. i have tried looking for ferts through hydroponics places, but they only seem to have brand name multi nutrient fertilizers, not the plain chemical. ebay may also be possible, if i can find someone in australia who can send them. why is it so hard?

i will dose "a bit" every day just to give the plants something, until i can find some dry ferts somehow.

what about the flourish trace i am using? is that strong enough to have an effect on larger tanks, or is that a waste of money too? i technically don't have high light - 1.5wpg. but all my plants are reacting (growth rates, types of plants that thrive, etc) as if i had high light. so i don't know what to do

 

[dapellegrini]

Zezmo - nice spreadsheet! I am going to play around with it a bit.

Sweet...