Raising kH & gH with a constant drip w/c

[*Ci*]

In my new planted goldfish tank I’m planning to do a 2 gph constant drip from my tap, which has zero kH and gH. Ideally, goldfish do better with higher values and although they are adaptable, I need a way to increase the ranges somewhat.
My plan was to fill a 5 gal. bucket with aragonite gravel, oystershell and seriyu stones and drip into that, having it plumbed so the new water would have to move to the bottom then out the top and dripping from there into my sump. In theory, the water would be spending a couple of hours soaking in the media, thereby raising kH and gH.

However, my tests are not showing much of an increase, barely 1-2 degrees of each. So I need to formulate a plan B, and I do not want it to be mixing dry salts into a liquid and using a dosing pump. This tank is supposed to be the epitome of low maintenance and that feels like too much work.

Any ideas? Is there something different I could put into the drip bucket? Could I just dump into the main tank an amount of calcium chloride and mag. sulphate to equal to whats needed for a daily 48g w/c? What would be the pros and cons of that? Not sure what to do about kH - maybe way more seriyu stone in the bucket?
Help, please!

 

[Koan]

Not sure what to do about kH

Well to raise KH, potassium carbonate works great

4.5 grams of K2CO3 in 48 gallons of water raises KH by 1 dKH or 17.9 ppm. It's very soluble, you can set the GH and KH to the baseline level you want, and then dump your dose replacement straight in

Depending on hardscaping your 48g turnover on 130 gallons is what, ~30-35% daily?

So if you set your baseline GH and KH at 8, the water could dilute to 6 over the course of the day before you added replenishment. That amount of fluctuation in GH and KH over the course of a day should not be an issue for high mass animals like goldfish

 

[*Ci*]

Thanks for the response and for doing the math for me : )
The tank is 115g, but the entire system works out to be about 175-180g.
Is it better to use potassium carbonate over sodium bicarbonate, which is easier to come by and cheaper?

And, just to be clear, I would scoop in all the dry powders once a day and it will only vary by about 2 degrees over the course of 24 hours?

It sounds easy but I wonder how tired I will get of doing that every day …

 

[Pepere]

I would be using baking soda at about a buck a pound vs potassium bicarcobate at $12.00 @ pound…

What is your target GH and KH?

Is livestock in the tank now? Or will you be getting it ready before adding livestock?

 

[Koan]

It sounds easy but I wonder how tired I will get of doing that every day …

You can shake it in the same time you feed the fish , @Naturescapes_Rocco has a super sexy way to measure out a whole bunch of the powders in advance so you just dump a little cup in

Post in thread 'Remineralizing RODI'

Dec 17, 2025

If you do the same volume of water change, you can prepare dry salts weeks in advance in one sitting:

Makes it easy!

• Naturescapes_Rocco

• 

baking soda at about a buck a pound vs potassium bicarcobate at $12.00 @ pound

$20CAN / kg from a Vintner Supply in Burnaby, @9g / dose that's about $6 a month

Potassium is better for your plants

And, just to be clear, I would scoop in all the dry powders once a day and it will only vary by about 2 degrees over the course of 24 hours?

Yes

 

[Pepere]

Could I just dump into the main tank an amount of calcium chloride and mag. sulphate to equal to whats needed for a daily 48g w/c?

I use CaSO4 and epsom salts. Calcium chloride is fine as well.

When I WC 50 gallons when I do my weekly water change, I weigh out my epsom salts and CaSO4 into half a gallon of water and add my dechlorinator in it and mix well.

I set it on top of my opened canopy with rigid airline in the pitcher and attached to flexible airline where the end is near my inlet adding new water to the tank. I allow siphon to add compounds into the water as tank fills.


When pitcher gets low I pull out airline, fill it with tank water to slosh around the pitcher to mix up CaSO4 sludge left behind and pour the water across the length of the tank..

 

[Phish Tank]

Maybe I missed something, but seems like if you want to eliminate daily fussing with Powders you'd whip up a stock solution and feed it in via a dosing pump?

In your aragonite gravel test, it will only dissolve if the Ph is acidic, I also wonder if adding a circulation pump to the 5 gallon bucket would speed things up with dissolving.

 

[JacksonL]

Maybe I missed something, but seems like if you want to eliminate daily fussing with Powders you'd whip up a stock solution and feed it in via a dosing pump?

This is the lowest maintenance option.
If you use distilled water, or even RO, you could make a very concentrated solution that would last a long time without growing anything in the dosing bottle.

 

[Naturescapes_Rocco]

The only downside to premade remineralization powders is that they have poor solubility, so you need massive jugs of pure water to hold what could normally be held in tiny powder forms. For example:

You can only dissolve ~2.4g of CaSO4*2H2O (Gypsum) in 1,000mL of pure water at 78F.

If I mixed a 1,000mL bottle with 2.4g CaSO4 (basically maximum, or even above max, at room temp), and dosed 100mL doses of this solution into a 50 gallon aquarium, I'd only be raising the Ca by 1.12ppm in my aquarium. That's for every 100mL doses. If I dumped the entire bottle into my 50Gal tank, I'd raise the Ca by 12ppm.

That's why so many of us just remineralize via dry dosing, instead of making solutions, for Ca/Mg/HCO3 salts.

 

[*Ci*]

How about this then - can I pre-mix a large amount of dry calcium chloride, epsom salts and baking powder in a large tub and then use one simple scoop of this mix per day? That seems doable and not too fussy.
Are they safe to mix together? Iy seems to me like there is something bad about adding baking soda and calcium chloride at the same time … ?

 

[Naturescapes_Rocco]

How about this then - can I pre-mix a large amount of dry calcium chloride, epsom salts and baking powder in a large tub and then use one simple scoop of this mix per day? That seems doable and not too fussy.

This is how other remineralizers do it! APT Sky, Seachem Equilibrium, etc... However, they use machines to absolutely pulverize these salts/crystals into a fine, homogenous powder. If you were to use MgSO4 (epsom salts) normally, you'd see that the large crystals are nothing like the CaCl powder or the baking soda (not baking powder!). I suppose you could try to grind them yourself, or I bet somewhere online sells MgSO4 in powder form. But yes, what you're describing is what's sold commercially. I would be concerned with trying it with the raw crystals themselves, as there's almost no guarantee that you'll get a homogenous mixture when you scoop it unless it's been absolutely pulverized (like these industrially-produced remineralizers are) into powder.

Are they safe to mix together? Iy seems to me like there is something bad about adding baking soda and calcium chloride at the same time … ?

Yes, they're safe to mix together, especially as long as you keep them dry. Nothing horrible will happen if they get wet. I'm glad you're wary, though. People don't always know not to mix household chemicals. For example, mixing bleach and vinegar releases toxic chlorine gas. But in this case with dry salts, you're fine.

Also, if you're worried about any of this, just measure individual batches at a time as necessary:

It'll take you 30 minutes of work to prepare a few months worth of these super cheap salts as necessary.

 

[*Ci*]

I would be using baking soda at about a buck a pound vs potassium bicarcobate at $12.00 @ pound…

What is your target GH and KH?

Is livestock in the tank now? Or will you be getting it ready before adding livestock?

I would like to target around 8 for both values, but it somewhat depends on where I wind up buying my fish from and what they recommend.
No fish for a while. I want to establish robust root systems first and I think the k1 in the moving bed will take a while to cycle - maybe a couple of months. It won’t even start “moving” until it develops a bit of a biofilm and stops floating.

 

[JacksonL]

You can only dissolve ~2.4g of CaSO4*2H2O (Gypsum) in 1,000mL of pure water at 78F.

For sure…. But you can dissolve large amounts of CaCl2.
I put 164g into a 750ml amber bottle, and it is already dissolved by the time I have finished weighing the epsom salts for the Mg remineraliser.
I keep both 750ml bottles in my water change box and 20ml of each into the tank post-WC gives me about 5Gh with a 3:1 ratio.
I find it far simpler than weighing multiple tiny amounts into cups every month or so.
Many different ways to do things, obviously, but I always feel that the longer you can space out maintenance tasks the better.

 

[Naturescapes_Rocco]

For sure…. But you can dissolve large amounts of CaCl2.
I put 164g into a 750ml amber bottle, and it is already dissolved by the time I have finished weighing the epsom salts for the Mg remineraliser.
I keep both 750ml bottles in my water change box and 20ml of each into the tank post-WC gives me about 5Gh with a 3:1 ratio.
I find it far simpler than weighing multiple tiny amounts into cups every month or so.
Many different ways to do things, obviously, but I always feel that the longer you can space out maintenance tasks the better.

Now that's appealing to me! I started using a Macros solution for the same reason (measure ingredients once, good for months of dosing without needing to measure amounts again). I started looking into what you mentioned, and this is totally doable with CaCl2*2H2O and MgSO4*7H2O, both of which are plenty soluble.

However, for every 30ppm Ca you add, you are also adding 53ppm Cl. Is that not a lot of chlorine?


What I found is that 30ppm Cl is reported to be pretty high for sensitive plants, and most sources I find online say that you should keep Cl below 50ppm, even for terrestrial plants. Curious what your experience has been?

 

[JacksonL]

Now that's appealing to me! I started using a Macros solution for the same reason (measure ingredients once, good for months of dosing without needing to measure amounts again). I started looking into what you mentioned, and this is totally doable with CaCl2*2H2O and MgSO4*7H2O, both of which are plenty soluble.

However, for every 30ppm Ca you add, you are also adding 53ppm Cl. Is that not a lot of chlorine?
View attachment 13891

What I found is that 30ppm Cl is reported to be pretty high for sensitive plants, and most sources I find online say that you should keep Cl below 50ppm, even for terrestrial plants. Curious what your experience has been?

Chloride (Cl-), not chlorine (Cl2). There will be no free chlorine produced from the remineralising.
With my 50% weekly water changes, the amount I add to get 25ish ppm Ca, ends up as 20ish ppm of Cl for the whole tank, as it is being dosed across the whole 130L.
I have been using calcium chloride for about 4 or 5 years and haven’t had issues. I detest mucking around with gypsum!

 

[Naturescapes_Rocco]

My bad, I meant chloride.

With my 50% weekly water changes, the amount I add to get 25ish ppm Ca, ends up as 20ish ppm of Cl for the whole tank, as it is being dosed across the whole 130L.
I have been using calcium chloride for about 4 or 5 years and haven’t had issues. I detest mucking around with gypsum!

Help me out, how are you getting those numbers? I'd love to make this work for my tank, but I'm really adverse to 40+ ppm Cl- in the water column...

If you remineralize to 25ppm Ca, it's going to add 44ppm Cl-. Unless you're not using RO water entirely?

 

[JacksonL]

My bad, I meant chloride.

Help me out, how are you getting those numbers? I'd love to make this work for my tank, but I'm really adverse to 40+ ppm Cl- in the water column...
View attachment 13900
If you remineralize to 25ppm Ca, it's going to add 44ppm Cl-. Unless you're not using RO water entirely?

You’re right, my numbers were based on that 44ppm being spread across the whole tank, but with minimal uptake from plants and no other loss, it would be about 44ppm steady state.
I would be interested to hear if others are using it, and if anyone has had issues.
My understanding is that it isn’t until 100+ppm that plants have issues with chloride. It’s fairly commonly used in my small group of planted tank keeping mates.

 

[JacksonL]

Out of interest, here are my state’s water report numbers for the major suburbs.

Prior to switching to RO to lower my KH and have a bit more control, I used this in my tanks for years. Outside of the more temperamental plants (Pantenal, ludwigia white were the main struggles) I had no major concerns, and I don’t believe chlorides were the culprit.

 

[Naturescapes_Rocco]

Yeah, what I'm seeing online (and there is surprisingly little information/experiences shared with CaCl2 remineralization) is that anything under 100ppm Cl- is probably fine. There may be some sensitive plant species that are affected by 30ppm+ Cl-, but there isn't a comprehensive list.

I'm curious to try it still!

 

[*Ci*]

I think I will try this plan (when I finally get the system circulating):

- fill the drip bucket with seriyu stone or maybe even chunks of concrete to add whatever kH it’s going to add, and let the goldfish adapt to that level. Is there anything similar or better that would raise kH only?

- figure out my amounts for calcium chloride and magnesium sulphate, translate that to the equivalent spoonful/scoop, and dose them daily into the overflow box when I feed the fish.
I’ll have 2 large bins of them under the stand for easy scooping, and with the reduced flow at the bottom of the overflow (23” deep) they will probably dissolve slowly which will, maybe, add to the stability?

Right now, this feels like the cheapest and easiest method, with the least amount of overall work and hassle. Time will tell …