Another re-mineralizing RO water thread :) - The Planted Tank Forum
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post #1 of 3 (permalink) Old 06-25-2020, 05:45 PM Thread Starter
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Question Another re-mineralizing RO water thread :)

Hi there! I realize that this is probably somethign posted here a ton - first time poster.

I was reading a thread earlier this week that discussed re-mineralizing your water with food-grade epsom's salt, potassium bicarbonate, and calcium sulfate. Well, those things came in for me today, but I can't seem to find the thread that mentioned them!

What's generally advised per gallon?

This is a 36G bowfront that I've slowly been adjusting to the RO system - last water change, its TDS was at 104 (down from almost 300!).

I'm keeping German Rams, a few danios, some neons, guppies, and harlequin rasboras, in addition to a myriad of plants.

According to test strips:

pH 6.8
GH/KH both 0
Nitrates: 20ppm
Nitrites: 0ppm
Ammonia: 0ppm

Thanks in advance!

Edit to add: I also use pressurized CO2 injected by an atomic diffuser with a Fluval 207, and I dose every other day with Niloc Thrive (I use 4 pumps as I noticed pinholes in some of my plant leaves). My lighting is a Fluval 3.0 that's mostly using just its factory settings (though I do put the tank down "for a nap" around mid-day so I can have more lighting at night).
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post #2 of 3 (permalink) Old 06-25-2020, 06:39 PM
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2 FYI's.

You're mixing and matching species that prefer different water parameters. It will probably be OK, but just know that guppies and Danios prefer harder water than Rams, neons and Rasbora's. I've known both those species to live in soft water but it's not their preferred.

And pinholes might be coming from lack of Ca/Mg.

That said, head over to and use their nutrient dosing calculator. Do it once for the whole 34gal tank then again for the amount of water you change on a weekly basis.

You are shooting for a 2:1 ratio of CA:Mg. So play with the numbers until you get a dGh of around 8, possibly a bit higher since you have guppies. But not too high since you have Rams.

Here's my numbers for reference...

Kh: 1
Gh: 8
Tds: 167
After front loading ferts it's over 200. Keep in mind that those numbers are not absolute. Your actual values may vary due to testing inaccuracies.

To a 32gal bucket I add...

15.61 grams of CA
8.43 grams of Mg

And since I have a 1/16 teaspoon I measure out 1/2 + 1/16 teaspoon of Na bicarbonate to bump up the Kh just a tad so pH measurements are more accurate.

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post #3 of 3 (permalink) Old 06-27-2020, 07:04 PM Thread Starter
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Sorry for the delayed response! Work has been super hectic for me the last couple of days.

The guppies are generally kept in their own tank aside from the few in this tank that're mostly just dither fish; they're fairly hardy fish, so I cater more to the GBRs than I do with them (as you can see with my temperature param @ 82F). So, I'm catering more toward the softer water than the harder water in this case.

Awesome, thanks - I think that these measurements are a great starting point. I'll shoot for around 8 to start out with.
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