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Matsyendra

NPK Dry Fertilisers - Source or Substitute

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Hi all,

In Townsville here. I have just started adding macro nutrients to the tank (NPK) for my plants and am currently using Seachem Nitrogen, Phosphorous and Potassium. I have adequate light and CO2 injection, so the only part left of my equation is to keep up the nutrients.

Whilst Seachem products are easy to use, they are ridiculously expensive to use in the quantities needed.

I have tried to source dry fertilisers locally and it is near impossible because people are apparently making bombs with this stuff.

Does anybody know where I could get Potassium Nitrate (KNO3), Potassium Sulphate (K2SO4) and Mono Potassium Phosphate (KH2PO4) in dry form... OR... suitable substitutes to Seachem that are not going to send me bankrupt just so I can keep some plants alive...

Going onto the terrorist watch list doesn't sound like any fun either.

Thanks in advance for any suggestions.

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any rural supply / agricultural supply store can get all those in for you. some may be willing to sell it to you by the kilo, others will want you to buy the whole 25kg bag.

soluable potassium sulphate (K2SO4) they should already have.

mono-potassium phosphate (KH2PO4) is also sold as MKP so they may know it as that.

if your desperate for KNO3, (E)Bay has some but it is pricey compared to getting it from a rural supply store.

also current research has now determined that you do not need to dose K2SO4 in addition to KNO3.

because by dosing KNO3 alone, your getting your required amount of N, but also getting 3x the necessary amount of K.

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Thanks for the reply simmo2302. It did seem strange to me that I would need to add potassium as all three of them contain potassium, but so far with the research I have been doing these are the ones that have been suggested.

I was hoping to stay with dry ferts as I know exactly how much I would need to add to the tank to get to the desired levels, whereas with soluble I would probably need to do calculations. The fewer calculations I need to do the less chance of making mistakes. :D

25kg bags seem like a LOT to purchase and would probably last me forever... and then I would need to make sure I am storing it properly. Do these things require specific storage requirements?

I am completely new to this fertilising thing... I thought you just stuck 'em in and off they go... seems there is a bit more to it than that, so anything you can tell me would be appreciated. I just got tired of buying new plants every few weeks... so far with the Seachem, everything has been great... just too pricey.

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soluable is the one you want. all ingredients have to be soluable or they wont be available for your plants to absorb.

soluable doesnt mean you have to make a stock solution up, or it is in liquid form.

the soluable potassium sulphate is a dry powder that will disolve into your tank water when you dose so its then available for your plants.

the insoluable one will sit on the bottom and do nothing.

my local rural supply shop had both and explained the difference.

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A cheap DIY is to go to garden store and get osmocote native. Go to craft store and get clay. Make little balls of clay, insert a few osmocote granules, dry in sun and then insert into your substrate near plants. They get nutrients both from clay and osmocote. Cheap too

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You will still need trace elements mix with NPK.

You could try following an EI dosing routine or maybe a PMDD routine or DOSING WITH GRUBS if you google that it should be on the aquarium life forum. All depends on your circumstances.

Getting hold of all of those ingredients are a piece of piss. Ebay for your KNO3 just ebay potassium nitrate and buy from Australia and away you go!, and the chelated micronutrients, and also for the monopotassium phosphate try Dave at Aquagreen (he has both just not the KNO3).

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Thanks for the suggestions. Had no idea about osmocote native - is it easy to control the levels it releases or is it a hit and miss type thing? I also looked on Ebay... too easy.

As for trace elements.. I am happy to stay with Seachem for those. It is the macro's that want to burn a hole in the pocket.

I think eventually I will just approach the local agricultural supplier and buy a huge bag...

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Update,

Went ahead and bought a huge 25 kg bag of KNO3... $60 too cheap... it is going to last me about 10 YEARS. When dosing KNO3 you really don't need to dose extra K as it will provide all the potassium you need.

As for sourcing KH2PO4 that was harder... nobody had it, and the only place I could find that did wanted nearly $100 for a 25 kg bag which would last me 4 times longer than the KNO3... with a bit of research I decided to get my phosphate needs from FLEET ENEMA... who knew lol?

5 ml of that in my tank (~170 ltrs) lifts my phosphates to about 2.75...perfecto and only 5 bucks a bottle :D

Using EI for dosing which makes it so simple. Goodbye test kits...hello freedom from stress... well not quite, just got to sort out that CO2 issue now...

So, it's all sorted thanks for your help..

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