Need Advice on Adding Minerals to RO Water - Tropical Fish Keeping - Aquarium fish care and resources
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post #1 of 6 Old 08-09-2012, 03:44 PM Thread Starter
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Cool Need Advice on Adding Minerals to RO Water

Need some help regarding adding minerals to RO tank water.

My initial tank set up was tap, until discovering my water quality. I have been using straight RO for a little while. I have researched online, and discovered an informative article on this site as well, regarding the importance of minerals. We recently installed a soft water system. My reverse osmosis filters this same water.

Using the API 5 in 1 test strips, here's my results for my tap water, ro water, and tank water:
PH, Tap water=7.5+, RO and Tank=6.5+
GH, Tap=0, RO, Tank=0
KH, Tap=240!, RO=maybe 40 Tank=40
Nitrite, Tap, RO, Tank=0
Nitrate, Tap=40, RO=20?, Tank=40
Amonia, Tank=0

What are my best options? I came across a product, RO right 1000gm on Aquarium Guys site. I also recall a product, Seachem Trace Elements. And I read an article on basic water chemistry, live aquaria, which states the easiest way to add minerals is in the form of a calcium-based rock. I know some suggest using part tap water, but I am assuming this would not be a consideration for me. I'd appreciate some feedback.

So far, I have one live plant cluster which looks healthy. I had noticed a couple skeletized leaves recently, which are now non existent. I have not put my gravel back in since a recent amonia spike. I have a bio wheel, which I have added zeolite crystals. The fish are thriving, for now. Will it be possible to create a naturally balanced planted tank?

FYI, current tank mates include; 1-angel, 2- dwarf gouramis, 2- swords, 2-neon tetras, and 1-pleco.

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post #2 of 6 Old 08-09-2012, 04:06 PM
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When I used RO Water, I just used RO Right and dosed by what the container said.

I've heard from others that using RO water with no minerals is very bad for your plants, so that may be whats happened to the one.
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post #3 of 6 Old 08-09-2012, 08:39 PM
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Using stright up RO water is fine for the fish. It will take out all of the trace elements and extra minerals in the tap water to make it pure. If you wish to, you can add in trace elements to better replicate the fish's natural environment. With RO water you need to make sure that the ph is where you want it to be, so make sure you have the right products to manipulate the ph of the water.
Since the RO water is basically striped from all of its minerals and chemicals that plants need it is a very good idea to add those in. The big one to add in is Iron.
I am a big fan of seachem products because they have always worked exceptionaly well for me and have never let me down. I would recommend that you go to their website and look up their products for plants.
Also I would recommend getting the Neutral Regulator made by Seachem to add to the RO water before you put it in your tank, since you seem to have a pretty neutral community tank this would seem like a good idea.

A very likely possibility of your plants dying could be because of your pleco. They will eat your plants, even if there are other sources of food.

One more thing I would recommend is to get a better set of tests. The strip tests aren't really known for being the most accurate. API makes great tests that come in little droplett bottles with test tubes, and they aren't expensive.

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post #4 of 6 Old 08-10-2012, 01:09 PM
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The plant issue is most likely a lack of hard minerals, especially calcium which is essential to cell formation. Soft water fish don't need these minerals (what they do need will come in their food) but you have one problem here and that is the sword (presumably a swordtail) as livebearers need mineral in the water.

My first suggestion is to re-home the swordtail, either its own tank, to an aquarist friend or a store. The other fish are fine with very soft water, and messing around raising the GH just for one fish when the others are better off "as is" would not be something I would attempt.

So, leaving that, to the plants and fish. The water softener might be adding salts of various kinds and these can be as bad or worse than the hard minerals for fish and plants. So assuming you stay with RO water: can you get some tap water before it goes through the softener? And what is the GH and pH of this pre-softener tap water?

If the above is not feasible (the pH may be astronomically high, and with so high a KH this is not going to lower easily), then i would recommend using Seachem's Equilibrium in your RO water. I do this, as I have near-zero GH in my tap water. Which is fine for my soft water fish, but not the plants. There is not sufficient calcium and magnesium in liquid or tab fertilizers to make up for calcium/magnesium-deficient source water.

You only need to raise the GH to 4 or 5 dGH to suffice for the plants. So stem plants will do better a bit higher. But Equilibrium is expensive and there is no value to over-using it, so with a good selection of suitable plants this can work well.

Flourish Comprehensive Supplement will provide all the other nutrients in balance. I use it twice a week. Equilibrium i add with each water change, and I have now got the amount needed to keep each tank at 5 or 6 dGH.


Byron Hosking, BMus, MA
Vancouver, BC, Canada

The aquarist is one who must learn the ways of the biologist, the chemist, and the veterinarian. [unknown source]

Something we all need to remember: The fish you've acquired was quite happy not being owned by you, minding its own business. If you’re going to take it under your wing then you’re responsible for it. Every aspect of its life is under your control, from water quality and temperature to swimming space. [Nathan Hill in PFK]

Last edited by Byron; 08-10-2012 at 01:11 PM.
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post #5 of 6 Old 08-10-2012, 01:49 PM
In spite of a portion of what has been previously posted, you must treat RO water to add minerals and adjust for pH. RO, DI, RO/DI, rain water, and distilled water are all too pure to provide a healthy environment for fish.

Experts with far more knowledge and experience than most of us here have written volumes on fish metabolism through osmosis. Suffice it to say that fish health is not only determined by diet, but also by water quality...and part of that water quality is relative to pH and mineral content in the water.

I make deionized (DI) water with an API Tap Water Filter and also am now using rain water (in combination with my filtered well water). I treat these with Seachem Replenish and Seachem Neutral and Alkaline Regulators to add minerals and adjust pH. In my case, I add a capful of Replenish, 1 tsp of Neutral Regulator and 1 tsp. of Alkaline Regulator to each 5g of water used for water changes. I also add Seachem Fresh Trace when doing water changes, ensuring there is ample trace elements in the water.
I also agree with Byron that when using these 'special' waters, it is a very good idea to mix with good quality ground (tap) water to ensure a more natural water chemistry quality.


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post #6 of 6 Old 08-11-2012, 04:12 PM Thread Starter
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Thanks guys! I do have an outside line for my outdoor plants and landscape that doesn't run thru the soft water system! I will test it. I plan to get some new test kits today. I am going to check another LFS today to see if they have something other than the strips to check my GH. Initially, when I set up my tank using tap,(before the install of the soft water system), the PH was between 7.6 and 7.8. So maybe it's doable. But I will retest.

I want to balance the tank as naturally as possible. So it does make more sense to re-home the Swordtails. I am hoping to successfully add more Angelfish.

Thanks again.

Last edited by mxdee; 08-11-2012 at 04:14 PM. Reason: forgot a word..."before"
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