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Ok, RO water only, and tons of plants… what do I likely need to add to the water for both the fish, and plants???

Magnum Man

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So, in the bulk of my tanks now, I’m using only RO water, and in most of my tanks, I have a jungle of terrestrial plants growing out of them… I’ve been reluctant to add fertilizers for the plants, as most of my tanks are heavily stocked with fish, and I’ve chosen plants, that don’t seem to need additional fertilizers… everything has been going great, on all fronts, for about 9 months now… I've had to replace some plants, that didn't do well without the addition of a fertilizer, but all now, currently seem fine without the addition of chemicals or minerals... but I’m curious about the necessity of adding any minerals to the water, that the fish might need, long term… most of these are soft water fish, and everyone seems to be thriving,, just wondering if there might be something they need, that I’m not providing??? Base water, and water change water are now, 100% RO… I add Indian Almond leaves occasionally, and some peat beads usually mixed in with ceramic media, that I root the plants into, & I give everyone a varied diet
 
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What exact species are you keeping?
That will determine what if any minerals you need to add.
 
I keep a lot of species ( literally almost too many to list ) but these tanks contain... ( 1 tank of African river tetras, and African 3 line glass cats, there is an African Vampire shrimp in this tank, & several mature Armano shrimp ), ( 1 tank of South American Tetras, from Rummy Noses, to Pristellas, & Emperors also Dwarf Cichlids, both Rams & Apistos ) ( 1 tank of Asian Fish, mostly varied Hill Stream Loaches, lots of them... but also Panda Garras, Denison Barbs, & up to Tin Foil Barbs ) ( 1 tank of South American Dwarf and medium sized Cichlids / Geo's ) there are also several Plecos & Oto's, & Hypoptopomas, intermixed in these tanks... & ( 1 tank that contains my Bichir, & a school of assorted Silver Dollars ) & I have an Amazon Puffer in a small tank right now... & my shrimp, get mostly well water, so, I do have the ability, to blend in some rock hard well water if needed, I just choose not to, at this time, for simplicity, & consistency
 
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Tank NumberSpeciesPreferred KH (dKH)Preferred GH (dGH)Preferred pH
1African River Tetras, 3-Line Glass Cats4-86-126.0 - 7.5
African Vampire Shrimp4-86-126.0 - 7.5
Amano Shrimp4-86-126.0 - 7.5
2Rummy Nose Tetras, Pristellas, Emperors3-64-86.0 - 7.0
Dwarf Cichlids (Rams & Apistos)3-64-85.5 - 7.0
3Hill Stream Loaches4-86-126.0 - 7.5
Panda Garras4-86-126.0 - 7.5
Denison Barbs4-86-126.0 - 7.5
Tin Foil Barbs4-86-126.0 - 7.5
4South American Dwarf/Medium Cichlids4-86-126.0 - 7.5
5Bichir & Silver Dollars4-86-126.0 - 7.5
6Amazon Puffer4-64-86.0 - 7.5
 
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so it sounds like I'm good there... water was hard to start with... it would take a long time of partial water changes to get the GH below 4... those numbers are roughly where I'm at on these tanks... if at some point, if notice my GH getting close to zero, I could just add a gallon of well water... assuming any micro nutrients, would come from staple foods, rather than the water
 
if at some point, if notice my GH getting close to zero

I wouldn't let the minerals crash down.

You will risk osmosis regulation problems, stunted growth, fin rot, buoyancy problems, plant nutrition deficiencies and PH swings. Missing minerals that fish need for healthy bones and gills, can cause them to lose electrolytes and fluids through their gills, leading to organ failure and death.

You have a good common ground on all your tanks to be able to make a "one mix fits all" recipe. It will help reduce the RO needed and prolong the life of your system media while insuring the best water conditions you can offer.

There is no place on earth where water is like RO. Even the softest sources likely contain some level of dissolved minerals and gases that RO water filtration removes entirely.
 
What is reverse osmosis and what does it do?
There's loads of information on this site and Google about reverse osmosis. Probably best you search for it and read through rather than someone copy and pasting it all here for you.
 
What is RO water?
Hi @Nuttawet . You've asked the same question in another thread, and gotten a good answer. Please, be patient and wait til you get answers to your questions. Posting the same question in several threads usually makes people stop answering.
 
so it sounds like I'm good there... water was hard to start with... it would take a long time of partial water changes to get the GH below 4... those numbers are roughly where I'm at on these tanks... if at some point, if notice my GH getting close to zero, I could just add a gallon of well water... assuming any micro nutrients, would come from staple foods, rather than the water
I would mix some well water with your RO, just not too high of a percentage to start until you get the hardness you are looking for.
 
As far as I know fish do not have a KH requirement. In our FW tanks most, if not all, of KH comes from carbonates and bicarbonates. The bacteria which need inorganic carbon can use these as can some plants. But fish have no requirements for these substances as far as I know.

What KH does is to keep the pH levels stable. So, if one wants to change the pH in a tank, they usually have to change the KH. RO water has almost no KH. My use of RO/DI water for my Altum angels is intended to produce two results. It lets me lower and maintain the pH of the tank at 6.0 despite it being 7.0 from my tap. Next, I want to lower the TDS of the water to keep it pretty soft. TDS is a measure of all the solids dissolved in the water. This includes both GH and KH and things not measured by either such as salt or organics. TDS is actually conductivity which has a formula applied to it to create the TDS number.

Because the KH determines the pH, it is important. However, the fish do not need any specific level of KH but maintaining a specific pH range is necessary for fish. They do have a need for a specific range of pH.

KH is often referred to as temporary hardness as it is easily changed when the carbonates or bicarbonates are taken up by bacteria and plants. They can also be neutralized by acids such as these produce by the cycle.

As for GH:
General Hardness

0 - 4 dH, 0 - 70 ppm : very soft
4 - 8 dH, 70 - 140 ppm : soft
8 - 12 dH, 140 - 210 ppm : medium hard
12 - 18 dH, 210 - 320 ppm : fairly hard
18 - 30 dH, 320 - 530 ppm : hard
higher : liquid rock (Lake Malawi and Los Angeles, CA)
I usually use 17.8 ppm for a degree of KH or GH to convert either to ppm. The chart above uses 17.5 ppm per dH. However, I tend to measure TDS rather than GH or KH. TDS includes both in the results. TDS also measures salt in the water which neither KH nor GH do. Salt is not the only thing that is in a tank that contributes to TDS but not to either of the other two measures.

Here is a pretty good read on all of this from the: Aquarium Water Quality: Total Alkalinity and Hardness
This link is from the more comprehensive information here Florida Department of Agriculture and Consumer Services: Aquarium Fish

Much of this information is also available here: Beginner FAQ: Practical Water Chemistry - What You Need to Know About Water Chemistry, and Why
 
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so it sounds like I'm good there... water was hard to start with... it would take a long time of partial water changes to get the GH below 4... those numbers are roughly where I'm at on these tanks... if at some point, if notice my GH getting close to zero, I could just add a gallon of well water... assuming any micro nutrients, would come from staple foods, rather than the water
Well water is the obvious solution to get it closer. I mix dry ferts and dose the liquid. (It works awesome and I am cheap). Anything is possible, but there is no way I could keep my water perfect without a lot of effort, and lab expense using pure RO. Seems unnecessary for most anyway. Depends on the fish species, but it doesn't take much of my well water to get the minerals reasonable for most fish and plants. EDIT: for my usual typos.
 
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Well water is the obvious solution to get it closer. I mix dry ferts and dose the liquid. (It works awesome and I am cheap). Anything is possible, but there is no way I could keep my water perfect without a lot of effort, and lab expense using pure RO. Seems unnecessary for most anyway. Depends on the fish species, but it doesn't take much of my well water to get the minerals reasonable for most fish and plants. EDIT: for my usual typos.

My well water was opposite. It was horrible for my fish. Naturally it was 20 plus degree gh. I had to run it through a softener, which of course then adds other treatments into the water. Then after a day, PH would raise to beyond 8 which I'm certain is CO2 offgassing so basically natural PH of the water was high. I live on a Peninsula where the bay is 600 feet from my house, leading to what I could assume was leaching. I ended up with RO/DI water solution and gotten it better.

I treat with Equilibriurm, Alkaline buffer, Flourish and Fresh Trace

Currently tank is 7 degree GH, 5 degree KH and 8.2 PH. PH high most likely from the CO2 offgassing. Checked with a drop checker and levels are very low. It shows in my plants.
 

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