Do I need both potassium nitrate and potassium sulfate? - The Planted Tank Forum
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post #1 of 30 (permalink) Old 02-05-2008, 12:32 PM Thread Starter
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Do I need both potassium nitrate and potassium sulfate?

I am going to be dosing EI method and I am fixing to buy some ferts. I have hard water so do I need equilibrium? Also like the title says do I need both kn03 and k2so4? I am asking b/c I dont wanna buy stuff I dont need thanks for the help.

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post #2 of 30 (permalink) Old 02-05-2008, 12:36 PM
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the amount of potassium in KNO3 is quite low and not usually promoted as a good dose for K. thats why most supplement with K2SO4. KNO3 is used primarily for the N, but if you get one of the fert calculators, you can account for the K in KNO3 when dosing K2SO4.

this also is the same for KH2PO4, which is used primarily to dose for phosphate, but you can account for the small amount of K dosed with it.

As far as equilibrium.... are you using pressurized CO2? How hard is the water? kH?


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post #3 of 30 (permalink) Old 02-05-2008, 12:36 PM
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You should be fine without needing to dose extra K. In theory, provided you're dosing EI without modification you'll have enough K from the KNO3 and the KH2PO4. I dose a bit less KH2PO4 because my tap has 1ppm of PO4 already, so I do add extra K.

Those with soft water, like myself, add Equilibrium to harden the water, so you wouldn't necessarily need it if you have hard water already. Tom Barr does recommend adding a little as a way to dose Ca & Mg, that's really a "it's your call" thing, just depending on how hard your water is.
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post #4 of 30 (permalink) Old 02-05-2008, 12:41 PM
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Quote:
Originally Posted by indiboi View Post
You should be fine without needing to dose extra K.
thats a bit premature, no? You can't really say he doesn't NEED K, we don't even know what his specs are, what plants he is growing, etc. With EI, you should be dosing in excess.

Now personally, I am with you on this approach, however, I would not stray from EI dosing regime as advice, especially for someone new to the hobby, or at least to these forums.


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post #5 of 30 (permalink) Old 02-05-2008, 12:45 PM
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The key to that statement is the sentence following it.

I direct you to the EI dosing guide written here:
http://www.barrreport.com/estimative...chy-folks.html

He does not list dosing K2SO4. To dose K2SO4 is to deviate.

Extra K is not added for the 'liquid method' here either:
http://www.barrreport.com/estimative...ei-dosing.html

I suppose it does depend on which EI Guide you follow, because there is one here that suggests adding it at a rate of ~2ppm. It's not even worth bothering with at such a rate unless it is to compensate for lower KH2PO4 dosing. (Worth the bother is, of course, my opinion and not based on any sort of scientific reasoning).
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post #6 of 30 (permalink) Old 02-05-2008, 12:49 PM Thread Starter
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This is a new tank and I will be running pressurized co2 and my cheapo test strip says my gh is 75ppm and my kh is 300 ppm. This is hard water right?
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post #7 of 30 (permalink) Old 02-05-2008, 12:53 PM
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There are 17.9ppm in one degree, so your water is ~4 degrees. I wouldn't call that hard, at all, I add Equilibrium to bring my tank up to that level.

*The 4 degrees here is for the GH only, as Equilibrium only effects that.
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post #8 of 30 (permalink) Old 02-05-2008, 12:57 PM
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Quote:
Originally Posted by JAXON777 View Post
This is a new tank and I will be running pressurized co2 and my cheapo test strip says my gh is 75ppm and my kh is 300 ppm. This is hard water right?
My goodness, are you absolutly correct that you did the test right? That kH is the highest I have ever seen.

I have to tell you, you are going to have a tough time with some plant species I think. Perhaps indi has some better advice for you here, but I would seriously consider doing something to this water to get that kH down down down. I consider my water hard and I have 125 ppm...lol.

There are aditives you can use to lower kH, but I personally would never reccomend them. The cleanest way to get it down is to cut your tap water with RO/DI water.

But again, I think you need some better advice from someone that has water like this and their experiences.

Sorry, but good luck!


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post #9 of 30 (permalink) Old 02-05-2008, 12:57 PM
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never mind, I didn't see your gH. water is soft actually. Your kH should drop with CO2 injection or by cutting with RO/Di water.

good link to read.

http://www.drhelm.com/aquarium/chemistry.html


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post #10 of 30 (permalink) Old 02-05-2008, 01:00 PM
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Indeed, that KH is off the chart. I would NOT rely on that figure though, since it was a test strip. An API KH/GH test kit is a couple bucks, the Hagen one for $10 is purportedly better in terms of color reading ability (at least for the GH part).

I was speaking of GH earlier, which is all that Equilibrium will effect, to be honest I didn't even notice the KH reading. I'm glad you pointed that out.

If your KH really is that high your PH would be off the chart high too, so use that as a 'check' if you will. Otherwise, as gmccreedy said, the only real way to "fix" that will be diluting your water with RO water.
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post #11 of 30 (permalink) Old 02-05-2008, 01:04 PM
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Quote:
Originally Posted by gmccreedy View Post
Your kH should drop with CO2 injection or by cutting with RO/Di water.

KH does not change with CO2, only the pH. This is how we can estimate CO2 levels, provided there are no other acids/buffers effecting the pH other than CO2.

Psst, not trying to give you a hard time, I swear!
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post #12 of 30 (permalink) Old 02-05-2008, 01:05 PM Thread Starter
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Well the test strip says ph is around 7.8 - 8.0 or so. I know this is a chepo test strip so take it for what its worth. I think I will get the equilibrium, this should be dosed during the w/c on sunday right?
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post #13 of 30 (permalink) Old 02-05-2008, 01:06 PM
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Seriously, I'd double check that KH reading with a liquid test before proceeding, it really would be worth your time. However; with a pH of ~8, then your KH would be about right at ~16.

It seems you have 'unconventional' water, most of the time the GH and KH are about even. So you appear to have soft water from the sense of minerals (GH), but you have very heavily buffered water, loaded with carbonates (KH).

That said, it doesn't hurt to have something on hand in the event you decide you need it, saves money on shipping at least in the long term.
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post #14 of 30 (permalink) Old 02-05-2008, 01:09 PM Thread Starter
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Cool thanks for the help. It is so nice to be able to ask questions and get exprienced help. (unlike my LFS)
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post #15 of 30 (permalink) Old 02-05-2008, 01:37 PM
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Since the KH is only a measure of the buffering, it wouldn't be effecting the fish directly like a high GH would. So you can ignore my earlier (now edited) mention that you'd possibly want to dilute the KH.

I still recommend checking against a liquid test though, so you have a more precise reading, my experience with those test strips is that they can be quite off.
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