RO / DI water in a planted aquarium

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Neptune555

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Nov 18, 2013
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I was thinking of using RO / DI water on my 50 gallon planted freshwater tank. My water is very hard as it is well water... and I have just struggled with high PH in my tank as a result. Tank parameters...GH 120 / KH 80 / PH 7.5 / Nitrite 0 / Nitrate 30 / Ammonia 0 / PH 7.0 - 7.5PH. If I switch to RO / DI water what supplements do I need to keep the plants and tank stable? Anyone use RO / DI water in a freshwater tank?

Neptune
 

FishFanMan

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I think you have medium hardness. It's softer than my lake Michigan water.
 

Byron Amazonas

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Yes, your GH at 120 equates to 6.7 dGH which is soft. This is absolutely ideal for plants. And not knowing what fish you have, it will work well for soft water fish too. [Hardwater fish (livebearers, rift lake etc) would not do well.]

To the pH, it is quite possible that as the tank becomes established, it will lower. The pH is somewhat "buffered" by the KH, but your KH of 80 ppm or 4 dKH is not that high. The breakdown of organics in the substrate produces CO2 naturally, and this tends to lower the pH.

You might be best to try things as they are. RO water is not without its issues, and regular water changes mean producing it in quantity, which can get expensive and time consuming. If you can work with what comes out of the tap, you will be better in the long run.

Byron.
 

Neptune555

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So yes my plants are thriving and I don't even have that much light on them. Lights are: 2 40 watt daylight bulbs. I placed a LED light from my 10 gallon tank just because it was not being used. I am not dosing w/ CO2 either but think I might add on DIY dose to get the banana plant to grow. I thought about upgrading the lights and adding CO2 but decided if it is not broke don't fix it. I have amazon swords and a vallisneria that is really filling up the tank nicely. Banana plant not doing well. Cabomba not doing well either. I would like a small foreground low lying grass if one could survive in these conditions any recommendations?

Here are the fish I have...
1 black knife fish - 5 years old
3 clown loaches - 3 months old
3 black mollies - NOT DOING WELL!
1 drawf gourami - 3 months old
1 male betta - 8 months old

i want to add more fish to my 50 gallon but wanted to figure out the water issue first. Can I add cardinal tetras? I just need a schooling fish.
 

Neptune555

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Nov 18, 2013
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Byron - My tank is old.. and the substrate from this tank is 5 years old... soil / vermiculite covered with river rocks to keep the soil in place. I wonder why the pH is so high? so recommendations on fish would be very happily received... I thought with a high PH that I could not get fish that wanted soft water.

Neptune
 

TL1000RSquid

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I use seachem's equilibrium with my RODI water, add's back the needed minerals and what not for plants. my waters softer then yours, didn't notice much of a difference on the plants, originally did it more for my shrimp seemed to make them breed a bit more.
 

Byron Amazonas

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Several questions/issues. I'll start with the mollies. They will not live long in this soft water, so no surprise they are not doing well. I would remove them, to avoid slow deaths which I don't like to see in fish.

To the plants. First, the Banana; this is not an easy plant for many of us. Even Dr. Kasselmann writes that it only lasts about a year for her, and she is a professional botanist. Some people seem to have better luck with this plant than others. Second, the Cabomba; this is a high light plant, and with that usually comes higher nutrients including CO2. Third, swords and Vallisneria tend to do fine in moderate light. I have poor results with Vallisneria because of my very soft water. It is around 7 ppm or 0.5 dGH, and when I last had this plant it slowly melted. I am now raising the GH in two tanks to around 5 dGH (for the large swords) and think I should try the Vall again to see if it fares better. Way back (1985) I had this plant growing like a weed in a small tank with calcareous substrate (dolomite), not surprising since it does occur in hard water such as the African rift lakes. Your GH may be sufficient to keep it healthy.

To plants in general. Many aquarists try to accommodate too wide a variety of plants, and some may do well while others don't. Plants like fish have varying requirements, though with plants light is the main factor; but as I noted for the Vall above, sometimes the water parameters are important too. But light is generally the issue, followed by nutrients. We must remember that varying the light intensity also affects the nutrient balance. Low light-requiring plants, moderate light-requiring and high light-requiring plants will not generally do well together; low and moderate, dor moderate and high, can sometimes work. The "middle road" is a bit more easy with plants than fish with differing needs, but still present. Algae is always waiting to take advantage of this situation.

Over the years I have tried many plants under my light. Swords (except for the red leaf species) do very well, as do crypts generally. Java Moss, Java Fern, Anubias do well but only if in shade; but I have floating plants in all my tanks so this is covered. Pennywort is the only stem plant that thrives for me, as there is insufficient light for the others I have tried such as Cabomba, several of the Hygrophila, Ludwigia, etc. Decide what you want in terms of plant appearance, then provide the necessary light and nutrients. And with higher light than what you now have, you will probably need to consider CO2. I have never bothered with diffused CO2 and have no intention of ever messing with it, as I don't need it for what I want. Photos attached below show what can be done without it. I have managed to balance the light and other nutrients with the natural CO2.

Now to the pH. Most of us wouldn't call this "high" if the numbers you gave of 7.0 to 7.5 are correct. I assume the tap and tank are in the same range? Did you out-gas the CO2 from the tap water before testing pH?

The vermiculite might be raising the pH. I'm not sure what mineral this is exactly, but I believe I have seen references to magnesium, silicates, and others that could increase pH and/or GH. This could be very minimal, but sufficient to prevent the natural lowering of pH as I mentioned previously (breakdown of organics). Your answer on out-gassing CO2 from tap water may clue us in here.

Fish are more affected by GH than pH, provided the latter is not way off. And you have no issues with GH for the fish mentioned, except the mollies. And if the pH remains around 7, this is fine too. However, it is wise to always know what is actually occurring in the aquarium with respect to pH, to avoid sudden problems.

Byron.

90g Oct 17-13.JPG 70g Feb 27-14.JPG
 

Neptune555

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Byron, beautiful tank! Wow all that and no CO2 inspired!
Yes I think I will remove mollies and let the tank work with out the RO/DI water. Going to do a 30% water change tonight b/c I was battling a small ich outbreak that come with my new clown loaches. After watching tank for a few more weeks I am going to try and get a school of tetras.

freshwater fishtank full view 2014.JPG

freshwater fishtank full view 2014.JPG freshwater fishtank 2014.JPG
 

Byron Amazonas

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Byron, beautiful tank! Wow all that and no CO2 inspired!
Yes I think I will remove mollies and let the tank work with out the RO/DI water. Going to do a 30% water change tonight b/c I was battling a small ich outbreak that come with my new clown loaches. After watching tank for a few more weeks I am going to try and get a school of tetras.
Thank you. Yes, I would not mess with what is obviously working for you. Light is fine (I have the same, two 48-inch T8 tubes 6500K, over my 4-foot 70g, 90g and 5-foot 115g). You don't mention fertilization, but so far you may not need it, or may be providing sufficient if you are. Swords are heavy feeders, and a root tab does wonders, but they will still manage if not as vigorously without. Nutrients occur from fish foods and water changes, and can be sufficient depending.

Byron.
 

Byron Amazonas

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I use seachem's equilibrium with my RODI water, add's back the needed minerals and what not for plants. my waters softer then yours, didn't notice much of a difference on the plants, originally did it more for my shrimp seemed to make them breed a bit more.
I'm also using Equilibrium in three tanks. My water is very soft, out of the tap the GH is 7 ppm which is basically zero, and I found that this doesn't bother the fish (I have all soft water fish, most are wild caught too) or most of the plants, but the larger swords were not receiving sufficient calcium especially; they develop brown spots which are iron deposits due to lack of calcium, and if left alone slowly kill the leaves and the plant. So I raise the GH to around 4 or 5 dGH in these tanks, problem solved as you can see from those photos. The calcium and other "hard" minerals in fertilizers are not sufficient to provide for the plant's needs.

Equilibrium is a good product, though I would prefer a liquid to avoid clouding the water every water change, but it passes. Seachem now have a liquid in their new line Aquavitro, but per volume it is very expensive by comparison. I have to count the pennies.

Byron.
 
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