GH

[BenB]

My GH is 11. It is 2 from the tap. I see people post that theirs is 4-6
I don't understand how my GH is so much higher than everyone else's.
Every 50% water change, I dose Ca and Mg to get in the EI range as per Rotalla Butterfly, but maybe I should be doing a half dose after the first one.
I've never seen people write about GH accumulation. Obviously it's a thing, but how do people keep theirs at 4 or 5?
I feel like I'm missing something basic here.
Note: I don't have any Seriyu stone in my tank.

 

[Pepere]

I have 2 degree GH tap water as well. I do 2/3 water change weekly. I only dose Calcium and Magnesium as I refill the tank to raise Ca to 30 pm and 6 ppm Mg.. I do not dose extra Calcium or Magnesium through the week.

 

[JayP]

The GH in my main display tank runs 12-13. I remineralize my RO for water changes at a fraction of the recommended dosage. I have a lot of Seiryu stone but no more than I see in many professional scapes so it's a bit of a mystery to me as well. Plants, fish, and Amano shrimp seem to be happy though, so it-is-what-it-is.

 

[ElleDee]

Hmm, any chance you are calculating your dose for the entire volume of the aquarium and not just the water being replaced? That would cause your levels to accumulate to twice the concentration you had in mind.

 

[Unexpected]

Don't dose GH per tank volume, dose per water change volume. Maybe a touch more to account for uptake but even then, just slightly. I'm assuming you do weekly water changes?

 

[Asher E.]

My GH is 11. It is 2 from the tap. I see people post that theirs is 4-6
I don't understand how my GH is so much higher than everyone else's.
Every 50% water change, I dose Ca and Mg to get in the EI range as per Rotalla Butterfly, but maybe I should be doing a half dose after the first one.
I've never seen people write about GH accumulation. Obviously it's a thing, but how do people keep theirs at 4 or 5?
I feel like I'm missing something basic here.
Note: I don't have any Seriyu stone in my tank.

I have tested on an ei tank, after 2 weeks with no water changes the gh stayed the same.
So as long as you have at least around 4dGH you shouldn’t need to dose any calcium or magnesium.

 

[BenB]

Hmm, any chance you are calculating your dose for the entire volume of the aquarium and not just the water being replaced? That would cause your levels to accumulate to twice the concentration you had in mind.

Yeah, I was dosing for tank volume. I know they don't take up that much, but I still thought you had to allow for some depletion like with other ferts. Also, see question about K below.

Don't dose GH per tank volume, dose per water change volume. Maybe a touch more to account for uptake but even then, just slightly. I'm assuming you do weekly water changes?

That's what I'll start doing. I dose these with spoons, so it's not so accurate to start with. I'll keep an eye on it the first few times.

I feel like K is lumped in with GH even though it isn't really measured by GH. The uptake of K is more significant than Ca and Mg. Do you dose that only for replaced water or give more of that?

 

[ElleDee]

@BenB Honestly, the question of whether you are dosing to the entire volume or to the water change amount is irrelevant if your water changes are large and consistent. For example for a 50% WC you can think of it as dosing 10 ppm of whatever nutrient for the whole tank or 20 ppm for the changed water. It's the same amount of stuff going into the same tank that will be used at the same rate. Whether that amount is appropriate or not is a separate question.

If you do small and/or infrequent water changes then nutrients will have more time to wander off target, whether that's through accumulation or depletion. If the amount of water you remove varies a lot, always dosing to the full tank size will result in fluctuations in nutrient concentrations.

(I don't think that directly answered your question, sorry )