# What is the optimal ratio of RO And Tap water to refrain from adding minerals?



## EQUINOX (Nov 19, 2008)

Hey,
I've been gradually lowering KH with 100% of water changes in the past couple of months.
I'm worried that i might be missing on some nutrients which as Ca or other minerals that accommodate tap water..

As of now, KH is at 5.
Am I taking any risk right now?
How soon will I see the deficiency of lack of minerals (Ca, Mg etc.)?
What will be the optimal ratio of tap water and RO water?

I do add all other fertilizing - NPK, Iron and Micro.
Tank is 67 GAL, High-Tech.

Thanks.


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## geeks_15 (Dec 9, 2006)

It depends on the make up of your tap water. If the water is moderately to very hard, you only need a small percentage of tap water mixed with RO water. You will most likely need to experiment some by mixing different ratios of RO water and tap water to figure it out. Also keep in mind that some tap water can change due to season or treatment by you local water supplier.

If your goal is to soften the water for the plants then a KH of 5 should be fine and many plants will grow well in this. I would also test GH to get a more complete picture of your water hardness.

I have some tanks with very soft water. This limits the types of plant species that I can grow in the tanks, but several grow quite well. So nutrient deficiencies will be plant species dependent.

In my high tech tank where I want to grow many different species I keep the water hardness moderately soft/hard and the plants do very well.


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## EQUINOX (Nov 19, 2008)

Thanks for the reply.
I got a few stems of SYNGONANTHUS SP. 'BELEM' from a friend.
They threw some side shoots at first (probably still still in just because the good conditions in their previous home) but then growth stagnated and they became yellow.
Same thing with ERIOCAULON SETACEUM..

What are the "must have" additives when using 100% RO?


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## Diana K (Dec 20, 2007)

If there is no other source of any nutrients then I would do a full EI program through the week:
N, P, K (macros)three days per week
Ca, Mg, Fe, and all the others. (micros) such as CSM + B and extra iron three days per week

You cannot look at KH and determine GH. These two tests measure totally different things. 

Baking soda and Seachem Equilibrium at water change time to make KH and GH at least 3 degrees. (depends on the fish and plants- Harder water, both sorts, if you are keeping hard water fish)

Don't forget the carbon! Excel or CO2.


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## EQUINOX (Nov 19, 2008)

> If there is no other source of any nutrients then I would do a full EI program through the week:
> N, P, K (macros)three days per week
> Ca, Mg, Fe, and all the others. (micros) such as CSM + B and extra iron three days per week


Thanks, I'll consider that. Does Seachem's Flourish contain enough of the Micros which i'm missing without tap water?
I guess not when it comes to Ca.



> *You cannot look at KH and determine GH. These two tests measure totally different things. *


Of course, I can't. I have a GH test as well. I'll check and report.



> Baking soda and Seachem Equilibrium at water change time to make KH and GH at least 3 degrees. (depends on the fish and plants- Harder water, both sorts, if you are keeping hard water fish)


I'd like to be around KH 2-3 but I'm a bit afraid of huge PH fluctuations.
Still I want to be able to grow SYNGONANTHUS and ERIOCAULON.



> Don't forget the carbon! Excel or CO2


Check here - Lots of CO2 

("THE" Diana?)


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## Diana K (Dec 20, 2007)

Not Diana Walstad, no. 

Form most tanks KH of about 3 degrees is better for more stable pH, but 2 degrees might be OK, just keep track of it, and if it is not working for you maybe you will have to raise it a bit. 
For really soft water plants, then yes, keep the GH really low, too. This will probably mean that you will not be able to grow any hard water plants in this tank. Val, for example dies without Ca.


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## EQUINOX (Nov 19, 2008)

Okay, I'm willing to stay with the "softies"..
Anyway Is GH affected only by Ca?


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## Diana K (Dec 20, 2007)

GH is a measure of calcium and magnesium. 

some fertilizer regimes suggest adding Epsom salt. This is a good source of Mg, but is not balanced by Ca. 
Most plants prefer a ratio of roughly 4 Ca: 1 Mg. The plants you want do not like Ca, but I have no idea if the want Mg or not. Probably not, but more research is suggested. 

Do not just add Epsom salt just because a fertilizer system says to. Your GH will climb, and plants that are so dependent on soft water (usually because of the Ca) probably won't want an excess of Mg, either.


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## EQUINOX (Nov 19, 2008)

Thanks.
I don't add any kind of salt (is "Epsom" the regular kitchen salt?)


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## DVS (Nov 20, 2005)

Epsom salt is magnesium sulfate, available at most drug stores, sometimes used as a component of bath salts.


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## EQUINOX (Nov 19, 2008)

Thanks.
I'd be happy to hear people's "recipes" when combining RO and tap water, what additives etc..


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## Diana K (Dec 20, 2007)

There is no one recipe, but here is a way to figure out pretty close to the ratio you will want to reach a certain GH or KH. The method is the same for GH and KH; I will work with the KH = 5 degrees, since that is your starting point. 

Add: The % RO x 0 (zero degrees of KH) + % Tap x 5 degrees

Example: 
25% RO + 75% tap
.25*0 + .75*5 = 3.75
This mix will create water with a KH of almost 4 degrees. 

Example: 
50% RO + 50% tap
.5*0 + .5*5 = 2.5
This mix will create water with a KH of about 2.5 degrees. 

When I had my RO filter running I would mix 50/50 tap and filter to soften the water for several species of fish, and then would keep the water in a garbage can and add a nylon stocking (Knee hi) of peat moss and circulate the water for 24-48 hours. Rams and many other black water fish really thrived in it. 

Tap: GH and KH around 5 degrees, pH high 7s. 
Mixed with RO and circulated with peat moss: GH and KH about 2-3 degrees, pH mid 6s.


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