# Reconstituting RO water....?



## Naja002 (Nov 15, 2005)

I finally broke weak and purchased an RO+DI system. I am wanting/needing a Ph of around 6-6.2--Maybe a little higher, maybe a little lower, but right now that's my mark.

I have Barr's GH Booster, so I will be using that, at least until its gone....So I need to understand what I am doing......

I am assuming that I want a KH of about 4, Correct? What about GH?--what am I looking for there?

I've read a ton of threads here and at TPT, but its all kind of gotten jumbled around in my head.

What am I looking for for KH and GH with a PH of 6-6.2 without C02?

TIA


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## chiahead (Dec 18, 2004)

Barrs GH booster will not boost your KH. It will boost your GH.


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## Ajax (Apr 3, 2006)

Seachem's equilibrium is specifically designed to reconstitute RO water.


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## Themuleous (Jun 6, 2006)

Save yourself the hassel and expense. Unless you are looking to get a very specific KH and GH readings, mix the RO water with your tap water. Thats what I do and its uber easy. Just test the GH and KH for your tap water, say this comes out at GH15 and KH12 (nice easy numbers) to get a KH of 4 (or a third of the tap water KH) you mix the RO to tap water at a ratio of 1:2 ie 1lt tap water with 2lt RO, that will give you GH5 and KH3. Its just case of diluting the tap water by the right amount. This should save you having to buy expensive re-mineralising products. It also will mean you get some trace elements from the tap water that will be missing from the re-mineral product (it cant contain EVERY element necessary!)

Sam


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## Naja002 (Nov 15, 2005)

Ok, so basically, Knowing the parameters of my Tap--I can just do the simple math to determine Gh and Kh by mixing the RODI with my tap, correct?

If so, My tap is : Ph ~8.2, Kh ~14-15, Gh ~17-18. So, if I say Kh is 15 and Gh is 18, then:

(1:3RO) would give me roughly Kh 4-(3.75) and Gh 4.5 correct? Then I test the actual mix to verify and either live with it or adjust it and do more testing, correct?

If the Ph turns out Higher than I am wanting--How do I lower it without lowering the Kh or adding C02?

Thanx!


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## elaphe (Aug 24, 2006)

If you're like me, my water changes daily. A few months ago I had about 500ppm TDS, pH around 8, and I stopped counting drops on the GH and KH test kits.

Now it's over 880ppm TDS and a pH of 9 - *liquid rock*. Even my RO filter is having a hard time getting below 10ppm TDS. At 500ppm TDS, I could get 0 to 1ppm TDS out of it. I'm also having to change my pre-filters a lot more now too.

I use RO/DI water with Barr's GH booster and Arm and Hammer baking soda for the KH. With running my CO2 at 40ppm, my pH comes in around 6.3 to 6.5.

Some of us have no option but RO/DI. I guess I could raise Africans with my tap water, but not much else.

BTW - The Barr's is the same as Seachem's Equilibrium, just a whole lot cheaper. I used the directions from the Seachem bottle for the Barr's and get the same results.

Brian


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## random_alias (Nov 7, 2005)

> If the Ph turns out Higher than I am wanting--How do I lower it without lowering the Kh or adding C02?


Realistically, you don't.

Aquasoil lowers PH but it does it by affecting KH I believe. Co2 lowers PH because the Co2 mixes with H20 to form carbonic acid. You could technically lower your PH by adding an acid to your water. This is troublesome and can be dangerous to flora/fauna if not done correctly and monitored. It can cause Ph changes as the acid mixes with the bases (carbonates) (KH) in your water and becomes neutralized. Then the PH goes back up quickly, you test your water an notice this change, add more acid, PH lowers, then increases again, etc. It's a hassle and highly discouraged. Much better to have stable water parameters, even if they are slightly outside of your target range.

You can soak peat in your water but that takes lots of time, is unpredictable, messy, etc. and then it leaves your water tea colored with tannins.

If you want total control of your fresh water PH without using Co2, you are going to have to do it by manipulating KH, ie keeping the PH low by keeping the KH low.


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## Salt (Apr 5, 2005)

Don't worry about the pH. Instead worry only about GH and KH. Recent findings suggest that a pH "crash" due to low KH is a myth. It was discovered that many tanks with Aqua Soil are set up with tap water which already has a low KH, then the Aqua Soil lowers it to 0, and plants and fish stay healthy and happy.

If you reconstitute pure RO/DI water to 1 dKH, the water will have a pH of around 7. There's no way to get it to 6.2 without adding CO2 or some other type of non carbonate based acid.

The other thing is to watch the magnesium levels. Some plants stop growing when magnesium gets higher than arround 10 ppm (44 ppm as CaCO3).

Right now I reconstitute my RO water with CaCO3 (not from Greg Watson as that is actually dolomite which can have high magnesium levels) to 60 ppm and that's pretty much it.


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## Naja002 (Nov 15, 2005)

> If you want total control of your fresh water PH without using Co2, you are going to have to do it by manipulating KH, ie keeping the PH low by keeping the KH low.


Ok, so this is what I am coming to realize.

So, I guess I will try mixing my tap with RO and shoot for a Kh of 2-3 and see where that gets me. I may be willing to pull the airstone out of the main tank as the Hornwort (oxygenator) gains more mass--that should help maintain C02 and 02 levels in the main tank and help reduce Ph. If I'm not happy with that I can start using Seachem's Acid Buffer again and keep adding buffer (Kh) via Baking soda as the acid buffer chews away at it. Yes, I will be going around in circles, but I guess I am just going to have to play this out and see what works and what is worth while. I don't have any objections to adding a C02 reactor to the main tank, but with the airstone running right now---there isn't much point.

How do these Biotopes maintain Ph's below 6 in nature?


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## random_alias (Nov 7, 2005)

Natural Co2 sources like springs and biological Co2 sources like bacteria breaking down decaying matter. Also decaying of plant matter that falls into the water and releases its tannins.

So, the same way we do, Co2 and acids.


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## Naja002 (Nov 15, 2005)

Ok, well, I already add Humic acids and Tannins for their antiseptic qualities--so that will help. I think I basically understand now what I needed to...so Thanx! everybody for the Help! Its just going to take some experimenting on my part to sort out what is what, what is workable, etc, etc, etc. Nothing seems to be simple!

Finally, with a low Kh and Ph--soft water--what kind of Gh am I looking for for the plants? Hygro polysperma, Hs 'ceylon', Anachrias, Hornwort and Weeping Moss.


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## BryceM (Nov 6, 2005)

GH is less important. A reasonable level is maybe somewhere around 3-5 (without proof), but lower or higher will work fine. Like Salt said, just be aware of the Ca/Mg ratio and absolute Mg concentration. Somewhere in the neighborhood of 3:1 or 4:1 is considered (again, without proof) to be pretty good.


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## TWood (Dec 9, 2004)

Salt said:


> The other thing is to watch the magnesium levels. Some plants stop growing when magnesium gets higher than arround 10 ppm (44 ppm as CaCO3).


Can you link to a reference for this? I'm not saying you're wrong, I'd just like to read more.

Thanks

EDIT: The reason I ask is that our water report shows Magnesium at 50ppm and Calcium at 83ppm. Those are the actual values, not as CaCO3. The water tests at about 23dGH, so that's consistent. I've suspected for some time that the magnesium is causing trouble.


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## JLudwig (Feb 16, 2004)

Ajax said:


> Seachem's equilibrium is specifically designed to reconstitute RO water.


Actually, I was with Nathan at the convention this year when he spoke to George Batten, Seachem's research chemist, about this very topic. I believe George said that equilibrium is not for *completely* reconstituting RO water, and that they were still working on a product to do this. My understanding from the conversation was that equilibrium is a supplement for softer water, but can do some squirrelly things if used by itself. Its probably best to cut the RO water 1/2 or 1/4 with tap to get the desired hardness, and add equilibrium to taste. I would encourage you to get into touch with Seachem directly for more info.

As for those who claim that water hardness doesn't matter, nor does pH, I would ask them kindly to provide some quantitative data supporting this claim 

Jeff


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## gnatster (Mar 6, 2004)

As Jeff stated above I did ask George Batten about reconstituting RO water and the issues I had in chasing pH, gh and kH values. George did say that Equlibrium along with the buffers is not enough. He explained to me why I was chasing the values I was looking for but at this time could not offer a simple way to achive my goals. As Jeff stated, they are working on a product. I have no details on a time frame, nor did I ask. They know there is a market for it and when the product is right they will bring it out.


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## Salt (Apr 5, 2005)

TWood said:


> Can you link to a reference for this? I'm not saying you're wrong, I'd just like to read more.


http://www.aquaticplantcentral.com/...calcium-magnesium-relationship.html#post69306


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