Do I need to add minerals to RO water?

[kross]

I'm getting back into the hobby after a 10 year hiatus, and I am now in an area with hard well water (about 14 degrees GH and KH), and will be using RO/DI water, since I want soft water fish (cories, tetras, rasboras, gouramis, etc.)

I have CO2, and bags of macro and micro dry ferts from years ago when I was doing EI dosing. I was fortunate in that the tap water was soft, so I didn't have to do anything special with the tap water. But now that I will be using an RO/DI filter, do I need to add minerals back into the water? And if so, what do I use? Seachem Equilibrium?

Oh, I forgot to mention, I will be using a sand substrate. I haven't decided on rocks for a hardscape yet. Maybe I should decide what rocks I will be using, and see how they affect the water parameters.

 

[Lynnzer]

Before you decide to go the RO route, I suggest you do a lot of thinking on exactly what fish you really want to keep. You may end up spending money on RO and stuff when the water may be OK for some species of fish you like.
14 degrees isn't too bad anyway. That equates to around 250ppm and that's well able to allow a good number of species to live very well. My own is at around 400ppm but I get that down to around 150 - 170 by adding bottled water to my tap water, or in 1 of my tanks I just use rainwater.

 

[Colin_T]

Most fish do better with some minerals in the water, even soft water fishes like tetras. However, they don't need much.

Since you already have medium hard water and are going to remove the minerals with reverse osmosis (R/O), just add some normal well water to the R/O water to give it some minerals.

You could do 2 parts R/O water and 1 part well water for a nice 80ppm water. That would give you some GH and KH to help stabilise the pH, but it's still low enough not to cause any problems to the fish.

You could even do a 50/50 mix of R/O and well water to give you water with 125ppm GH. Again it would be fine for most soft water fishes unless you want to breed some of the tetras.

 

[kross]

Do to the logistics of using well water, that would be a major hassle, more so than using RO water and adding minerals. The only source of unsoftened water is the outdoor hose faucet. I live in northern Michigan, and I don't want to be running a hose from outside into my house every week in the 6 months of winter. It's a 75g tank.

 

[hansgruber7]

I use RO water and I add Seachem Equilibrium and I also add PH stabilizers and that's it. Seems to work well for me.

 

[Back in the fold]

I use straight R/O water in my tanks with Aplocheilus lineatus Golden Wonder Killifish. Also one 4 gallon tank that I inherited from a grand daughter who wearied of it. It had 5 Neon Tetras in it but their numbers have dwindled to 2 in the past months. All fish are thriving. The Java Fern and Java Moss are thriving and I could probably get away with straight tap water but I like really clean well filtered water and my fish are rain forest soft water types too. You don't need to add minerals back. Personal preference. Go with your gut.

 

[StevenF]

Fish need the same nutrients your plants need sodding EI dosing is a good start to reminerlizing your water. However keep in mind that EI dosing recommendations were to dose NPK and micros (typically CSM+B). But that ignored several macro nutrients (calcium, magnesium and sulfur and chlorine (very low levels) which are all needed forby plants . Additionally CSM+B used iron EDTA. But Iron EDTA only works it the water PH is 6.5 or less. For many tanks you cannot get to that PH. So many people today are using iron DTPA with is good up to a PH of 7.5 and maybe up to 8. And also CSM+B has been found to be low on zinc.

I would recommend you get a new micro, GLA micro is very similar to CSM+B but with DTPA and zinc added. 1 dose a week of this fertilizer should be sufficient for most tanks.

For calcium and magneisum a Gh booster can be used. But I made my own with calcium magensium chloride and calcium sulfate. This would satisfy the Ca, Mgm S,cl need of your plants. Dose the minimum you need I currently like to dose 2ppm Mg and 6ppm ca. Put a decorative sea shell in the tank any excess sulfate or chloride in the water will be neutralized by the se shell. Don't use a KH booster.


that should work with100% RO water.

 

[kross]

For calcium and magneisum a Gh booster can be used. But I made my own with calcium magensium chloride and calcium sulfate.

@StevenF I tried searching for calcium magnesium chloride but came up empty. Is that a typo? Did you mean magnesium chloride (MgCl2) and calcium sulfate?

 

[Colin_T]

calcium chloride and magnesium chloride if you are trying to increase the GH (general hardness) of the water.

no idea about calcium sulphate (sulfate)

 

[StevenF]

@StevenF I tried searching for calcium magnesium chloride but came up empty. Is that a typo? Did you mean magnesium chloride (MgCl2) and calcium sulfate?

You can get MgCl2 and CaSO4 from this Loudwolf.com. A good source for all your macro needs and they sell most of the chemicals in small bottle so you don't need to buy a years supply of one nutrient. P

lants like a Ca Mg ratio of 1 part magnesium to 3 parts calcium. I like to do about 2ppm Ca CL2 and and 6ppm CaSO4. I used this nutrient-calculator. and a small milligram scale to calculate and measure out the ingredients. this will satisfy the plants need for Ca, Mg, Cl and S. But it provides more S and CL than needed and the excess can make the water acidic.

I Solved the PH problem by putting a sea shell in th e filter. The Sea shell would react with the Excess S and Cl and neutralize the acidity. Using the sea shell My tanks PH stays close close to 7. But keep in mind the the traditional CSM+B that is widely used in EL tanks has iron EDTA which breaks down at a PH higher than 6.5. If that is what you have then you need to target a PH of about 6. I use Iron DTPA which is stable up to a PH of 7.5. I have to replace these shell about once a year and a small bag of shells didn't cost much as the pet store.

Seachem Equilibrium is made of CaSO4 and MgSO4. in the Mg Cl ratio I used. Equilibrim also adds iron, and potassium which you do not need. Other GH boosters on the market use CaCl2 and MgCl2.

 

[seangee]

I have soft water fish in RO. No need to add anything. All 4 of my tanks are low tech / low light. The only thing I add (besides water) is root tabs when I remember.

 

[Byron]

I totally agree with @seangee above. My tap water for 30 years was zero GH/KH with (until recently) a pH around or below 5 (lowest I could measure). Soft and very soft water fish thrived. The plants however do need something, at least I found this to be the case, but not much. Liquid fertilizers obviously get in the water and thus inside fish so they should be kept minimal. Substrate tabs, at any rate Flourish Tabs by Seachem, do not dissolve into the upper water column so these benefit plants (and boy, do they) without harming fish.

Something that is now being said more and more is that addition of CO2 (in any form) and overdosing of fertilizers (like the EI method) is detrimental to very soft water fish. It makes no sense to be adding all this junk in order to supposedly improve plant growth when it is harming the fish.

 

[StevenF]

lants like a Ca Mg ratio of 1 part magnesium to 3 parts calcium. I like to do about 2ppm Ca CL2 and and 6ppm CaSO4.

I have soft water fish in RO. No need to add anything. All 4 of my tanks are low tech / low light. The only thing I add (besides water) is root tabs when I

Guys the dose I recommended that is less than 1/2 of a Degree of GH. Some RO systems (but not all) don't go down that low. Also some root tabs in include magnesium and calcium. Sachem root tabs which Byron use have calcium and magnesium chloride.

 

[TwoTankAmin]

Let me start by saying I have been using an RO/DI unit for a tank with altum angels for a number of years. So my first observation is that there is a difference between RO water and RO/DI water. The latter is purer. The DI resin remove ions. This would include ammonium (NH4+) the + means it has a positive charge. Plants love this form of ammonia whereas the bacteria prefer NH3 ammonia. Rhings which hage a charge, either positive or negative , is an Ion and will not be filtered out by an RO membrane.

Things we know about in our tank that are ions would include nitrite and nitrate and plants will use nitrate when ammonium, or its equivalent, is not available. Consider what determines the pH of our water:

The outcome of a pH-measurement is determined by a consideration between the number of H+ ions and the number of hydroxide (OH-) ions. When the number of H+ ions equals the number of OH- ions, the water is neutral. It will than have a pH of about 7.

https://www.lenntech.com/ph-and-alkalinity.htm

It is all about the ions. My unit removes ions, an RO unit alone does not. I would never keep any fish in 100% water from my RO/DI unit with nothing added back.

What this means is when I make my water and I test it for conductivity/TDS right away, I get a readin6 pretty much of 0. Testing RO it gives me a TDS reading of 10. (I intuit the ppm of TDS better than the microsiemens of conductivity).

So, water with ions in it is good for the plants and means it is not quite pure water.

I mix my RO/DI with my tap 11/9. My tap is 83 ppm TDS and pH 7.0. I keep the tank at a target of 6.0 and TDS in the 60s ppm. The water is stained and has no live plants. This make things easier for me. I do add rooibos to the water as well as alder cones and catappa leaves. Sometime I use muriatic acid to get the pH as low as I need it in the changing water. The tank pH tends to drift towards 6.5 between water changes.

I do add equilibrium to my planted tanks which have many assassin snails and amano shrimp as well as being heavily planted. Without the Equilibrium the plants and crustaceans are short of what they need.

As for being able to use presoftened water year round very easily you need to have two things. The first if the phone number of a local plumber and the second is the miney to pay then to put a faucet on the incoming line inside the house before the ssoftener. Conssider a garden hose type faucet so you can connect a hose to it with ease if you want.

Consider that fish have bones and then what its required to make bones and for them to grow. If you are curious about what your fish need and must get in adequate supply either from their diet and/or the water. One way or the other certain nutrients/mnerals/lements must be available for fish. These may be in for ot the water and may easily be transfered between them in some cases.

Then further consider what plants require as well, and it should be clear that it is impossible for either to live in pure water, i.e. only Hydrogen and Oxygen, for any length of time. At the very least there will be other dissolved gasses as well. CO2 will get into the water almost as soon as it comes out of an Ro or RO/DI unit into the open air.