# What to add to RO water



## andusbeckus (16 Dec 2016)

I have set up and cycled my planted tank but have decided to use RO water as I want to keep green neons so I need soft water and I feel better knowing exactly what is going in my water.

My question is what do I need to add to my RO water? Is something like Seachem Equilibrium enough on its own or do I need to add anything else?


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## three-fingers (16 Dec 2016)

Add tap water to your RO water to add some minerals back, just add like 10-30% tap water depending on how hard your tap water is.

Equilibrium is fine (I add a bit to my soft tap water when required), but if your using RO water because your tap water is already very hard then you already essentially have pre-mixed Equilibrium on-tap.


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## andusbeckus (17 Dec 2016)

I'd rather just use 100% RO water so I know exactly what is in there (I'm a bit OCD like that lol) plus I get a horrible build up of limescale if I use tap so want to eliminate that.

If I add equilibrium would I need to add anything else like PH buffer? I need soft water eith PH of around 6.5 so would it be ok just add add equilibrium and nothing else?


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## Andy D (17 Dec 2016)

Personally I follow THIS


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## Costa (17 Dec 2016)

Before going into the RO trouble, check with your fish vendor. They may be keeping the tetras in regular tap water, they very often do. Ofcourse RO is ideal, but it's expensive, messy and wastes a lot of water. 

You can use regular peat moss to soften the water if you want (I do). My tetras have bread twice in my tanks.


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## andusbeckus (17 Dec 2016)

I've already decided to use RO water so cost isn't a problem. I really just want to know if I need anytging other than one product such as Equilibrium or whether I need anytging else. 

I don't want the hassle of DIY minerals either measuring everything out.


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## Costa (17 Dec 2016)

OK then


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## andusbeckus (17 Dec 2016)

Costa said:


> OK then


Sorry if that sounded a bit blunt but sometimes it's like asking for advice about a dog and someone saying "have you considered a cat?"


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## Costa (17 Dec 2016)

No worries mate, it did sound a little blunt but I know how forum posts often can be misunderstood so no problem!! I was simply stating the fact that RO will be a PITA in the long term and you will likely find yourself resorting to more natural ways of lowering your water hardness and pH (like the peat I mentioned). 

I have zero hands on experience with RO - from what I have read the key is to find the ratio between tap:RO water to reach the hardness you need for your fishes. Also TDS (like impurities) is very important, a properly working RO system produces less than 150 TDS. 

Again I'm nowhere near an expert, so let's wait to hear from the seasoned professionals!

Best of luck with your tank


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## three-fingers (17 Dec 2016)

andusbeckus said:


> I'd rather just use 100% RO water so I know exactly what is in there (I'm a bit OCD like that lol) plus I get a horrible build up of limescale if I use tap so want to eliminate that.
> 
> If I add equilibrium would I need to add anything else like PH buffer? I need soft water eith PH of around 6.5 so would it be ok just add add equilibrium and nothing else?


But if you are adding anything like Equilibrium to the RO water, you wont be adding 100% RO water?   Using a small amount tap water vs. Equilibrium will make no difference to limescale accumulation.

Whether the minerals come from your tap water or an expensive commercial remineralisation product they have the same effect... If "OCD" is an issue...ask your water provider exactly what is in your tap water. I would trust their report more than I would trust aquarium product manufacturers ingredient lists anyway.  Given your suspicion of your tap water, I hope you don't drink it .

With soft water and plants, your pH will swing all over the place depending on the time of the day anyway, it's not realistic (or important) to aim for a specific pH.  There is much discussion of this on the forum about pH, such as this recent thread:

Contemplating CO2

(Even if you aren't adding CO2, this still applies as plants consume more CO2 this during the day).

Yes though, you can just add Equilibrium and nothing else if you want soft water but not pure RO. It provides pretty much the same end results as cutting the RO with tap water except it's more expensive, sometimes doesn't dissolve fully and is easier to get measurements wrong.  If you really "don't want the hassle of DIY minerals either measuring everything out" then just use tap water+RO, simple.


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## Costa (17 Dec 2016)

To elaborate a little on the previous post, water coming out of your RO should have both kH and GH at 0.

So if your tap is GH at 14 and kH at 9 and you need GH 4 and kH 2 then you should mix 1 part tap water with 3-3.5 parts RO water. There is a very nice article about water chemistry on UKAPS that explains which elements in your aquarium (like e.g. soil, ferts, wood) affect the GH and which affect the kH, I'll post here when I find it.

I don't think adding off the shelf solutions like the one you mentioned in your second post will be viable long term, in that they will leave you with a big hole in your wallet. Obviously this expense will be very small if your tank is small, but for bigger tanks (e.g. I have a 200gal tank) the costs skyrocket and it just doesn't make sense.

But then again, if you keep tetras (or discus) who like very soft water, you will achieve a beautiful biotope with crystal clear water (i.e. without the tanins from peat) and your fishes will be reproducing like mad (and tetras are very hard to get them to reproduce).

Also, pure RO is extremely dangerous. RO water has zero buffering capacity, so any solution in the tank (coming from wood, filter media, soil etc) can very quickly swing the pH and these changes that fast are not tolerable by the fish, especially the green neons.


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## three-fingers (17 Dec 2016)

I wouldn't say RO is extremely dangerous, certainly not for soft water fish anyway. As explained in the links above, pH swings are harmless to fish and unavoidable in planted tanks.

It's a different story in fish-only tanks (where a pH swing can be an indicator of something else gone bad) which is why people are traditionally scared of pH swings.


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## andusbeckus (18 Dec 2016)

three-fingers said:


> But if you are adding anything like Equilibrium to the RO water, you wont be adding 100% RO water?   Using a small amount tap water vs. Equilibrium will make no difference to limescale accumulation.



Obviously what I meant by 100% RO water was the fact I want to use 0% tap water  



> Whether the minerals come from your tap water or an expensive commercial remineralisation product they have the same effect... If "OCD" is an issue...ask your water provider exactly what is in your tap water. I would trust their report more than I would trust aquarium product manufacturers ingredient lists anyway.  Given your suspicion of your tap water, I hope you don't drink it .



I do drink my tap water but considering the fact I tested ammonia in it at one point last year I want to provide the best water quality I can for my fish. At least with RO water I know there wont be a chance of adding ammonia unless I accidentally piss in it!



> Yes though, you can just add Equilibrium and nothing else....



Thanks!


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## three-fingers (18 Dec 2016)

I understand your concerns now, with random ammonia in the tapwater, I would be hesitant to drink it tbh! 

When I worked at an LFS, we had a bunch of customers from one small area come in one week due to issues with ammonia in their tap water - I advised they report this to their water company, the next day the water company was providing their whole area (just a  few streets) with free bottled water until they fixed the problem!  Never found out what caused that ammonia (I thought it was maybe from biological degradation of chloramine, but none was being added apparently), but whatever it was was dangerous enough for the water company to spend loads on bottled water.

One you have a healthy plant mass though, a small amount of ammonia at a water change could actually be appreciated by the plants, escpecially if you are diluting it with RO. If you ever get tired of buying/measuring/mixing powders, don't worry too much about your tap water .


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## Henry (18 Dec 2016)

Jesus, can the guy just get a straight answer?

Add a complete buffer like JBL Aquadur or similar, along with your usual fertiliser. That's all you need.


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## ian_m (19 Dec 2016)

To cover all bases you should really dose your RO water with prime as a RO unit does not guarantee complete removal of the water supplies dechlorinator. The big boy reefers sometimes dose their stored RO water with dechlorinator and sometimes Amquel (for ammonia) in case there is an issue with the water and/or RO system.

The RO issues are:

1. If incoming water is treated with chlorine and hopefully you are frequently replaced incoming RO carbon filter, it will successfully remove the chlorine before the membrane. If your carbon filter is exhausted (hope you are monitoring its usage ????) chlorine gets through and destroys the RO membrane and gets through into the RO output water. Some big boy reefers check RO with chlorine test kits (swimming pool test kits ) before putting RO into their tanks.They pre-store the RO water first and test (and remineralise & salt) before putting into their tanks. When marine fish cost £300 each, it pays to check the water and always add Prime and/or Amquel+.

2. If incoming water is treated with chloramine there are bigger issues. If you are using an incoming Dechlor+ carbon filter (and not exhausted) this slower flow carbon filter will break down the chloramine to chlorine and ammonia and absorb these in the carbon and all is OK. However, if flow is too fast and/or prefilter exhausted the ammonia will not be absorbed and pass right through into the RO water. If you are using a normal carbon filter is may/will possibly let ammonia through anyway. Big boy reefers again check their stored RO water for ammonia before use or just bung in Prime and/or Amquel+.

It has been reported many times in the reef forums of people using RO water wiping all their fish out due to these issues, one guy lost £1000 of marine fish due to ammonia in his RO water from water board emergency water sterilisation by addition of chloramine.

Output DI resins can help alleviate the above problems, but again the resins have to be in tip top condition for them to work. Or just bung in Prime and/or Amquel+.

I found out this from local fish shop as the owner was showing me his equipment  and I noticed test kits near the RO storage containers. This was to test the stored RO water for presence of chlorine or ammonia. And yes he had found chlorine once in the RO water due to a faulty filter, he assumed water was getting past the filter somehow. Anyway never had any issues, just change the incoming Dechlor+ filters and DI resin regularly and no problem.


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