Potassium, Potassium, Potassium - The Planted Tank Forum
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post #1 of 13 (permalink) Old 07-18-2018, 09:17 PM Thread Starter
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Hi all, just wanted to run something by the forum.

Currently I am using RO/DI water from my SW setup and just reconstituting it with Seachem Equilibrium and Baking soda. I'm only now realizing that I may be hitting my tank with way too much potassium though.

I add about 34 ppm of K via the Seachem Equilibrium to my tank each water change in order to have my GH at 6. I then add about 18 ppm per week via fertilization. That's a total of 52 ppm of K every week! I never really thought about the K I was adding with Equilibrium, but that seems like an awful lot for the much lower calcium that is being added in (14 ppm).

My thought was to decrease my GH to about 3 to add only 17 ppm of K via Equilibrium, then add the 18 ppm per week via fertilization to hit 35 ppm per week (still a bit high, but not sure how to decrease it without making my water absurdly soft).

Plants are growing, just not looking amazing, to be honest. I am starting to gain some ground on an algae issue I have been fighting with good husbandry, though. I am under the impression that adding 52 ppm of K every week as I have erroneously been doing may be screwing up my plants' ability to absorb other nutrients.

Thanks for looking... what do you think?

Also, that would only be adding 7 ppm of Calcium per week, which I'm not sure is enough. Looks like from reading old anecdotal posts it might be, but I'm hoping for someone with much more experience than me to clear that up. Thanks again for any help!

Last edited by Darkblade48; 07-20-2018 at 12:00 AM. Reason: Please use the edit function for back to back posts to keep threads cleaner
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post #2 of 13 (permalink) Old 07-18-2018, 11:47 PM
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First of all, excess K is generally not a problem (at least for me).

That being said, you could pick up some MgSO4 and CaSO4 and raise the GH without adding any K. And as a bonus it's much cheaper in the long run.

I also use RO water and I dose mine to Ca 35ppm and Mg 13ppm. But you will find out what works for you.

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I am starting to gain some ground on an algae issue I have been fighting with good husbandry, though.
And keep up with the husbandry. It's easily the fastest way to an algae free tank.
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post #3 of 13 (permalink) Old 07-18-2018, 11:57 PM Thread Starter
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Originally Posted by Greggz View Post
First of all, excess K is generally not a problem (at least for me).

That being said, you could pick up some MgSO4 and CaSO4 and raise the GH without adding any K. And as a bonus it's much cheaper in the long run.

I also use RO water and I dose mine to Ca 35ppm and Mg 13ppm. But you will find out what works for you.


And keep up with the husbandry. It's easily the fastest way to an algae free tank.


Excellent, thank you so much for the help. That sounds like a good idea with adding the sulfates, maybe I will switch to doing that. My current GH and KH are 8 and 5 respectively, and I am currently in the process of lowering those slowly to a target of 4 dGH and 0-2 dKH as I've read many people keep their levels this low and see positive impacts on their plants. I know Dennis Wong recently stated one of his tanks is 3-5 dGH and 0-1 or 2 dGH. Hoping emulating one of the greats will give me a bit better return on my investment .
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post #4 of 13 (permalink) Old 07-19-2018, 12:17 AM
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I know Dennis Wong recently stated one of his tanks is 3-5 dGH and 0-1 or 2 dGH. Hoping emulating one of the greats will give me a bit better return on my investment .
Dennis surely is one to follow, and I do as well.

But if you are going to try and emulate what he does, you need to study up on EVERYTHING he does. Substrate/lighting/ferts/flow/CO2/plant selection/pruning/fish load/maintenance, etc.......and did I say maintenance.......because that is uber important in his tanks.

I'm only pointing out that the GH and KH of Dennis's tanks is one tiny little piece of a larger pie.


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post #5 of 13 (permalink) Old 07-19-2018, 12:44 AM
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Lots of potassium probably doesn't hurt, but there are some indications that it can inhibit uptake of some nutrients, such as magnesium. To be on the safe side, I try to maintain about 30ppm. I add 15ppm after each 50% water change to hit that 30ppm maintenance level.

As @Greggz mentioned, you can get to your GH objective without the Equilibrium and here is how I do it:
- .9ppm calcium from calcium chloride. This gives me just a little chloride (1.6ppm) that is good for the plants.
- 7.6ppm calcium gluconate. The gluconate form makes the calcium immediately available.
- 3ppm magnesium sulfate (Epsom salt)

Remember; doing a 50% water change means that I add half the amount of what I want to maintain. So, what I've added (above) to the RODI water amounts to 1.5 degrees GH. Theoretically, I already have 1.5dGH after the 50% water change. So, my total GH, after adding the above, is 3 dGH. I target a 3:1 Ca:Mg ratio. some prefer 4:1.

KH is another issue. I currently add no alkaline buffers, so my KH is zero. However, I used to maintain a 2 dKH level and did so by adding potassium bicarbonate (KHCO3). Most use baking soda, which is sodium bicarbonate. Sodium does not help plants, so I went with the KHCO3 to eliminate the sodium. If you do this, you will have to factor the extra potassium from this and knock down the loading of the K2SO4, above.

Do not mix calcium chloride with either magnesium sulfate or potasium bicarbonate in the pre-mix
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post #6 of 13 (permalink) Old 07-19-2018, 12:54 AM
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Originally Posted by Greggz View Post
Dennis surely is one to follow, and I do as well.

I'm only pointing out that the GH and KH of Dennis's tanks is one tiny little piece of a larger pie.
Keeping shrimp, GH of 5-6 is a win and plants will be happy.

Reducing KH IMHO is a huge piece of pie.
Many harder to grow species of plants appreciate the lower KH.
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Growing is not that difficult.
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post #7 of 13 (permalink) Old 07-19-2018, 01:00 AM Thread Starter
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Originally Posted by Greggz View Post
Dennis surely is one to follow, and I do as well.

But if you are going to try and emulate what he does, you need to study up on EVERYTHING he does. Substrate/lighting/ferts/flow/CO2/plant selection/pruning/fish load/maintenance, etc.......and did I say maintenance.......because that is uber important in his tanks.

I'm only pointing out that the GH and KH of Dennis's tanks is one tiny little piece of a larger pie.
Absolutely. I've been reading enough tank journals and spending enough time on his website to make my head spin. I definitely have seen improvement in the last month or two in my plants and I feel as if things are heading in the right direction, just not there yet. It's good advice that you're giving too. I sort of look at my tank as a mixture of a couple different poster's on the forum, and am using their success to tweak what I do in order to hopefully attain some of the same level of success.



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Lots of potassium probably doesn't hurt, but there are some indications that it can inhibit uptake of some nutrients, such as magnesium. To be on the safe side, I try to maintain about 30ppm. I add 15ppm after each 50% water change to hit that 30ppm maintenance level.

As @Greggz mentioned, you can get to your GH objective without the Equilibrium and here is how I do it:
- .9ppm calcium from calcium chloride. This gives me just a little chloride (1.6ppm) that is good for the plants.
- 7.6ppm calcium gluconate. The gluconate form makes the calcium immediately available.
- 3ppm magnesium sulfate (Epsom salt)

Remember; doing a 50% water change means that I add half the amount of what I want to maintain. So, what I've added (above) to the RODI water amounts to 1.5 degrees GH. Theoretically, I already have 1.5dGH after the 50% water change. So, my total GH, after adding the above, is 3 dGH. I target a 3:1 Ca:Mg ratio. some prefer 4:1.

KH is another issue. I currently add no alkaline buffers, so my KH is zero. However, I used to maintain a 2 dKH level and did so by adding potassium bicarbonate (KHCO3). Most use baking soda, which is sodium bicarbonate. Sodium does not help plants, so I went with the KHCO3 to eliminate the sodium. If you do this, you will have to factor the extra potassium from this and knock down the loading of the K2SO4, above.

Do not mix calcium chloride with either magnesium sulfate or potasium bicarbonate in the pre-mix
Thanks for explaining how you reconstitute the water, but I just have one question regarding the "total GH". My understanding is that the units of dGH are a standard measurement per volume, AKA a concentration, and therefore not additive by quantity alone without taking into account how much water is the divalent cations are dissolved in.

https://en.wikipedia.org/wiki/DGH

From Wiki: " General hardness is a measure of the concentration of divalent metal ions such as calcium (Ca2+) and magnesium (Mg2+) per volume of water. Specifically, 1 dGH is defined as 10 milligrams (mg) of calcium oxide (CaO) per litre of water."

Essentially, I believe this means that you cannot take 50% of your tank volume at 1.5 dGH + 50% of your tank volume at 1.5 dGH and say you have 3 dGH. Wouldn't you still have 1.5 dGH if you added these together? It's pouring two liquids together that have the same concentration, not changing the solute/solvent ratio. Am I not understanding this correctly? Thanks for the clarification!

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Quote:
Originally Posted by Maryland Guppy View Post
Keeping shrimp, GH of 5-6 is a win and plants will be happy.

Reducing KH IMHO is a huge piece of pie.
Many harder to grow species of plants appreciate the lower KH.

Perfect, that's exactly what I was hoping for! Wish I would have read this sooner! Hopefully I see positive changes soon.
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post #8 of 13 (permalink) Old 07-19-2018, 01:25 AM
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Originally Posted by cab395 View Post
Thanks for explaining how you reconstitute the water, but I just have one question regarding the "total GH". My understanding is that the units of dGH are a standard measurement per volume, AKA a concentration, and therefore not additive by quantity alone without taking into account how much water is the divalent cations are dissolved in.

https://en.wikipedia.org/wiki/DGH

From Wiki: " General hardness is a measure of the concentration of divalent metal ions such as calcium (Ca2+) and magnesium (Mg2+) per volume of water. Specifically, 1 dGH is defined as 10 milligrams (mg) of calcium oxide (CaO) per litre of water."

Essentially, I believe this means that you cannot take 50% of your tank volume at 1.5 dGH + 50% of your tank volume at 1.5 dGH and say you have 3 dGH. Wouldn't you still have 1.5 dGH if you added these together? It's pouring two liquids together that have the same concentration, not changing the solute/solvent ratio. Am I not understanding this correctly? Thanks for the clarification!
Doesn't work that way. Keep in mind that my focus was on ppm in order to achieve a targeted dGH. If you were to measure my dGH after the 50% water change, you would find ~1.5 dGH. When you add my re-mineralization back in, it jumps back up to ~3 dGH.
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post #9 of 13 (permalink) Old 07-19-2018, 01:32 AM Thread Starter
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Doesn't work that way. Keep in mind that my focus was on ppm in order to achieve a targeted dGH. If you were to measure my dGH after the 50% water change, you would find ~1.5 dGH. When you add my re-mineralization back in, it jumps back up to ~3 dGH.
Ahh, I see, we are talking about two different things. I remineralize my RO water prior to adding it to the tank to match the tank's parameters, so when I add it it doesn't change. It sounds like you add RO water to your tank then remineralize it after you add it to the tank, which would make sense by how you described it. Thanks for the clarification!
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post #10 of 13 (permalink) Old 07-19-2018, 01:38 AM
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Originally Posted by cab395 View Post
Hi all, just wanted to run something by the forum.

Currently I am using RO/DI water from my SW setup and just reconstituting it with Seachem Equilibrium and Baking soda. I'm only now realizing that I may be hitting my tank with way too much potassium though.
You are right about the crazy high potassium concentrations causing problems. This is why you see some individual posts about increasing all of the other ion concentrations to combat these limitations. The secret is ratios.

Quote:
Originally Posted by Deanna View Post
Lots of potassium probably doesn't hurt, but there are some indications that it can inhibit uptake of some nutrients, such as magnesium.
Thatís right. And not only Mg but also N, Ca, Mn and B.

Quote:
Originally Posted by cab395 View Post
Also, that would only be adding 7 ppm of Calcium per week, which I'm not sure is enough.
Simply maintaining Ca at 20 Ė 30 ppm is all what is needed, CaSO4 does the trick. Plants can take 0.3 ppm a day so 20 Ė 30 ppm will cover that without worry.

Mg is best when supplied daily. The daily Mg uptake can be only 0.1 ppm, but high levels can cause problems like inhibiting Ca and K uptake.

Quote:
Originally Posted by cab395 View Post
My current GH and KH are 8 and 5 respectively, and I am currently in the process of lowering those slowly to a target of 4 dGH and 0-2 dKH as I've read many people keep their levels this low and see positive impacts on their plants. I know Dennis Wong recently stated one of his tanks is 3-5 dGH and 0-1 or 2 dGH. Hoping emulating one of the greats will give me a bit better return on my investment .
Yes, thatís the way to go.

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Originally Posted by Deanna View Post
KH is another issue. I currently add no alkaline buffers, so my KH is zero.
I always favored negligible KH. Substrate or a bit of coral is all what is needed to keep pH under control. Anyway, the best world aquariums have dKH bellow 1, go figure.

Deanna, how is it working for you so far?
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post #11 of 13 (permalink) Old 07-19-2018, 02:27 AM
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You are right about the crazy high potassium concentrations causing problems. This is why you see some individual posts about increasing all of the other ion concentrations to combat these limitations.
Edward what you call crazy high others call normal levels, and are quite successful with them.


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Last edited by Greggz; 07-19-2018 at 10:54 AM. Reason: typo
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post #12 of 13 (permalink) Old 07-19-2018, 03:53 AM
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Deanna, how is it working for you so far?
Well, I have a few things going on. I’ve been at zero KH for a few months with no negligible effects. My fish are producing enough waste to support a constant nitrate level of about 25-30ppm. However, a few weeks after dropping KH to zero, my nitrates dropped suddenly to the 5 ppm level and have not moved much since then. Plants are thriving with no addition of nitrogen products. So, I assume that the plants are taking the entire nitrogenous waste stream at this point. I’m going to hold K in the 30ppm area because I believe my fish continue to ‘dose’ N products in the 25-30ppm NO3-equivalent region.

I need to pump-in about 10ppm PO4 a week to keep it in the 4-5 ppm area. Heavy micros along the lines of @Greggz thread, but tuned more to Tropica’s ratios. I front-load everything after the weekly water change, except micros and iron (DTPA). Don’t want to go below 3 dGH due to fish considerations.

Simultaneously with the elimination of bicarbonates, I pushed pH below 6 with the intention of stalling the BB (along with lack of bicarbonates for the BB). Throughout all of this, for about a year now, no bio-media in my filter, just mechanical filtration (cleaned weekly).

I did get a noticeable kick in growth and GSA reduction over the last few weeks when I introduced a new CO2 diffusion approach (posted elsewhere) and abandoned my Griggs-style reactor. This created a further drop in my pH down to about 5.4. Obviously, due to increased CO2, but the fish show no sign of difficulty …unlike other attempts to lower pH via the reactor.

I think there are many ways to approach success, as is apparent with so many successful tanks (according to the proud pictures, anyway). I prefer working toward a minimal intervention status. Unfortunately, I like high light throughout the day (~80-90 PAR at the substrate, 12 hours/day), which does require intervention to keep algae subdued. So, I like what’s going on right now, but I’ll probably keep experimenting.
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post #13 of 13 (permalink) Old 07-19-2018, 02:07 PM
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Well, I have a few things going on. Iíve been at zero KH for a few months with no negligible effects. My fish are producing enough waste to support a constant nitrate level of about 25-30ppm. However, a few weeks after dropping KH to zero, my nitrates dropped suddenly to the 5 ppm level and have not moved much since then. Plants are thriving with no addition of nitrogen products. So, I assume that the plants are taking the entire nitrogenous waste stream at this point. Iím going to hold K in the 30ppm area because I believe my fish continue to Ďdoseí N products in the 25-30ppm NO3-equivalent region.

I need to pump-in about 10ppm PO4 a week to keep it in the 4-5 ppm area. Heavy micros along the lines of @Greggz thread, but tuned more to Tropicaís ratios. I front-load everything after the weekly water change, except micros and iron (DTPA). Donít want to go below 3 dGH due to fish considerations.

Simultaneously with the elimination of bicarbonates, I pushed pH below 6 with the intention of stalling the BB (along with lack of bicarbonates for the BB). Throughout all of this, for about a year now, no bio-media in my filter, just mechanical filtration (cleaned weekly).

I did get a noticeable kick in growth and GSA reduction over the last few weeks when I introduced a new CO2 diffusion approach (posted elsewhere) and abandoned my Griggs-style reactor. This created a further drop in my pH down to about 5.4. Obviously, due to increased CO2, but the fish show no sign of difficulty Öunlike other attempts to lower pH via the reactor.

I think there are many ways to approach success, as is apparent with so many successful tanks (according to the proud pictures, anyway). I prefer working toward a minimal intervention status. Unfortunately, I like high light throughout the day (~80-90 PAR at the substrate, 12 hours/day), which does require intervention to keep algae subdued. So, I like whatís going on right now, but Iíll probably keep experimenting.
Deanna, great results and excellent description, thank you.

Last edited by Edward; 07-19-2018 at 05:10 PM. Reason: .
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