Lowering KH

[Sb1415]

Hi,

So I am preparing the inhabitants of my 29 gallon planted tank with fish (tetras/rasboras/platy/corys/otos) to be transferred to a new tank in the next few weeks. My current tank has a high Gh and Kh (both >15 dKh on the API gh/kh test) and high pH due to hard tap water in a tank with inert substrate. My plan is to use aqua soil and RO water in the new tank with a KH <5. But I would like to use my existing plants and fish.

Trying to see how gradually to change the parameters.

I brought the Kh down to 13 yesterday with using some RO during water change (7 gallon RO for a 15 gallon water change and rest tap water). Everybody is doing ok.

I am planning to do another one in 2-3 days where I take out 7 gallon and refill with 7 gallon of RO water which I think should bring the Kh down to 8-10, and then another similar one in next 2-3 days to bring it to target.

What do you guys think ?

 

[Naturescapes_Rocco]

Making slow changes with KH is important, so you're doing well. GH can swing pretty readily but KH swings will absolutely kill inhabitants if they happen too fast.

I run all zero (or near zero) KH tanks, using just RO water. Make sure you're remineralizing your RO water as you add it!
I aim for 25ppm Ca and ~6ppm Mg. This has been great for plants, great for neocaridina and amano shrimp, great for fish and (ugh) pond/bladder snails, too.

 

[Sb1415]

Making slow changes with KH is important, so you're doing well. GH can swing pretty readily but KH swings will absolutely kill inhabitants if they happen too fast.

I run all zero (or near zero) KH tanks, using just RO water. Make sure you're remineralizing your RO water as you add it!
I aim for 25ppm Ca and ~6ppm Mg. This has been great for plants, great for neocaridina and amano shrimp, great for fish and (ugh) pond/bladder snails, too.

Thank you!
How do you add fish from to your aquarium from the LFS since their kh is not probably not zero ?

Do you add things like seachem equibilirum to the RO reservoir or to the aquarium after adding the RO water ?

 

[Naturescapes_Rocco]

Thank you!
How do you add fish from to your aquarium from the LFS since their kh is not probably not zero ?

I use a Drip Acclimator from Innovative Marine (everyone should have one for <$20 tbh) and slowly drip acclimate the inhabitants over at least 2-3 hours.

Do you add things like seachem equibilirum to the RO reservoir or to the aquarium after adding the RO water ?

Yes, because GH is still important for plants and shrimp (and maybe fish a little!).
To raise my RO water GH from zero, I started with Seachem Equilibrium, but switched to APT Sky since it didn't add other things like Iron and dissolved better... until I learned how to use Rotala Butterfly and just do it for 1/10th the cost of these products!

Now, I can just buy my CaSO4 and MgSO4 for ~$5 and dose both separately will full control.

For water changes, I remove a known volume from the tank, fill it up with fresh RO water, then dose the CaSO4 and MgSO4 powders directly.
Well, I usually pre-mix the CaSO4 quickly in a glass of RO water or tank water to help dissolve it in advance before it enters the aquarium, since CaSO4 powder can clump up and take 24 hours to dissolve if you don't "pre-dissolve" it. But yea, just add the powders in after you've re-filled the tank.

Like I said, I aim for 25ppm Ca and ~6ppm Mg. Here's what my settings look like for my 70-gallon RO water changes for my big tank:

1. Enter your volume of fresh RO water on Rotala Butterfly calculator,
2. select DIY,
3. Select either CaSO4.2H2O or MgSO4.7H2O (aka gypsum and epsom salts. Don't select "CaSO4.1/2H2O")
4. select dry dosing
5. select dose to reach a target
6. set it to 25ppm for CaSO4.2H2O, and 6ppm Mg for MgSO4.7H2O
7. Hit calculate and see the results on the right hand side:

For my 70-gallon fresh RO water, I need to add 28.46g CaSO4 to reach 25ppm Ca.

This is also the same method you'd use for dosing NPK fertilizer powder/salts like KNO3, KH2PO4, K2SO4, etc!

 

[Sb1415]

I use a Drip Acclimator from Innovative Marine (everyone should have one for <$20 tbh) and slowly drip acclimate the inhabitants over at least 2-3 hours.

Yes, because GH is still important for plants and shrimp (and maybe fish a little!).
To raise my RO water GH from zero, I started with Seachem Equilibrium, but switched to APT Sky since it didn't add other things like Iron and dissolved better... until I learned how to use Rotala Butterfly and just do it for 1/10th the cost of these products!

Now, I can just buy my CaSO4 and MgSO4 for ~$5 and dose both separately will full control.

For water changes, I remove a known volume from the tank, fill it up with fresh RO water, then dose the CaSO4 and MgSO4 powders directly.
Well, I usually pre-mix the CaSO4 quickly in a glass of RO water or tank water to help dissolve it in advance before it enters the aquarium, since CaSO4 powder can clump up and take 24 hours to dissolve if you don't "pre-dissolve" it. But yea, just add the powders in after you've re-filled the tank.

Like I said, I aim for 25ppm Ca and ~6ppm Mg. Here's what my settings look like for my 70-gallon RO water changes for my big tank:
View attachment 9366

1. Enter your volume of fresh RO water on Rotala Butterfly calculator,
2. select DIY,
3. Select either CaSO4.2H2O or MgSO4.7H2O (aka gypsum and epsom salts. Don't select "CaSO4.1/2H2O")
4. select dry dosing
5. select dose to reach a target
6. set it to 25ppm for CaSO4.2H2O, and 6ppm Mg for MgSO4.7H2O
7. Hit calculate and see the results on the right hand side:

For my 70-gallon fresh RO water, I need to add 28.46g CaSO4 to reach 25ppm Ca.

This is also the same method you'd use for dosing NPK fertilizer powder/salts like KNO3, KH2PO4, K2SO4, etc!

Thanks for the masterclass on this! Much appreciated!!

Hopefully this can be saved in some sort of beginner must read !

Just ordered the Apt sky but will look more into manual dosing as I get deeper into it!! And ordering the drip acclimator!

I am assuming there is a scientific basis on how you came up with the calcium/magnesium ratio do you mind elaborating. What is the Ph that you run your tank at ?

 

[Naturescapes_Rocco]

I am assuming there is a scientific basis on how you came up with the calcium/magnesium ratio do you mind elaborating.

Just following the work of the greats who came before (many of whom are on this forum!). 25ppm Ca is enough for shrimps and plants, 6ppm Mg is enough for plants. Combined in RO water, they result in a GH of about 5-6. It's soft enough water to keep all my plants super healthy, while not stripping the water totally of Ca/Mg. Also a ratio of roughly 4:1 Ca:Mg is pretty common. It just works for me!

What is the Ph that you run your tank at ?

This is unrelated to the GH part, but my aquasoil tank is usually between 5.5pH and 6.5pH, while my sand tanks are between 6.0pH and 7.0pH.
I don't really care much about pH unless I'm using it to track/understand my CO2 injection. Otherwise, it doesn't really matter when using RO water and keeping a low KH!

 

[Sb1415]

Just following the work of the greats who came before (many of whom are on this forum!). 25ppm Ca is enough for shrimps and plants, 6ppm Mg is enough for plants. Combined in RO water, they result in a GH of about 5-6. It's soft enough water to keep all my plants super healthy, while not stripping the water totally of Ca/Mg. Also a ratio of roughly 4:1 Ca:Mg is pretty common. It just works for me!

This is unrelated to the GH part, but my aquasoil tank is usually between 5.5pH and 6.5pH, while my sand tanks are between 6.0pH and 7.0pH.
I don't really care much about pH unless I'm using it to track/understand my CO2 injection. Otherwise, it doesn't really matter when using RO water and keeping a low KH!

Kh - 4-5
GH - 10
TDS - 180
PH - 6-7
Nitrate - 0-5
Phosphate - 0-0.25
After 75% water change - aug 1st

Went great. Plants and fish survived. Used apt sky. Can’t get accurate numbers since I use the API kit which I think is not super reliable especially for the nitrates.

Thanks again