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Discussion Starter #1
Hi!

I have a 90g community planted tank which has been setup for the past 8 months or so. Presently I am following this dosing schedule:-

On the day of w/c - 10 mls of KNO3 (stock sol. of 8 tb spoons in 400 mls of Distillld water), 2 mls of KH2PO4 (stock sol. of 2 tb spoons in 400 mls of distilled water, 20 mls of Flourish Trace & 3 mls of Flourish Iron.

Repeat the same dosing on the 3rd or 4th day

I have reduced my dosing a bit as was having GDA problem.

Now for the past few weeks I am seeing holes on the old leaves of N. Japonica. The plant is growing quite well but then once the leaves become old they will evelop holes & the size of the holes will increase with time. I understand this is because of lack of Potassium.

From the dosing schedule of KNO3, I understand my tank is getting about 3 PPM of Potassium every week where as the required level is about 20 PPM. Thus, the balance amount has to come from dosing of K2SO4.

My question is how much K2SO4 should I dose to take care of this problem?

Thanks in advance for your help.
 

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If you feel that the level of potassium is too low I would recommend just getting a bottle of Seachem Potassium and dosing accordingly.

Good luck.

-Ryan
 

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Discussion Starter #3
Thanks Ryan for your prompt reply. Unfortunately the Seachem Products are not that easily available in India. The ones that I am currently using are got from Singapore. However, I do have a bottle of K2SO4 (lab grade) & can easily prepare a stock solution once I know what should be the dosing amount.
 

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Here is a link to Chuck Gadd's site. Many here dry dose K on water changes. Calculating dosages of fertilizer elements for a planted tank

It would be potassium in potassium sulfate. K has not been linked to causing algae, BTW.

I also found this in my notes... I think its from Rex's site. Rexgrigg.com

For dosing K2SO4 don't bother to mix a solution. Dose it dry. 1.5 grams or ¼ teaspoon of K2SO4 will dose 10 gallons of water to 17.72 ppm. Take a bit of your tank water and pour the K2SO4 into it. Then mix till dissolved and pour back into the tank. Hope this helps. bob
 

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Discussion Starter #5
Thanks Betowess for the information. I will follow your suggestion. By the way do we need to dose K2SO4 only once after w/c or also on the 3rd or the 4th day from w/c?
 

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Thanks Betowess for the information. I will follow your suggestion. By the way do we need to dose K2SO4 only once after w/c or also on the 3rd or the 4th day from w/c?
I use to dose it once a week when I prepped the water change or during the fill part. But some dose it once or twice or three times a week with the macros. Now I'm using one of the little powerheads with a plastic cereal container to dose K and KNO3 and traces automatically everynight with a digital timer- for one minute.It lasts three weeks between recharge. There is a thread in DIY by Wasserpest called autodosing for dummies or something like that. Pretty cool time saving small investment. I still dose PO4 with a dosing syringe because including PO4 reportedly makes it a stinky mess.

Here is a link to Rex's valuble site: Rex's Guide to Dosing Dry Ferts

Also, I think I use to just dose 1/2 slightly heaping teaspoon to 50 gallons and that worked fine. Goodluck!
 
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