# RO/DI Water



## Nystina (Nov 24, 2004)

Hello everyone, 
I have been reading some posts on the use of RO/DI water and it's quite confusing. 
My questions are.... i've read that KH is a problem with RO/DI water, how do you address this and what should I be aware of?

My LFS has advised me not to mix RO/DI with tap water. They say that high TDS are not optimum for a planted tank. Any thoughts on this?

I'm really just trying to find the best way to use RO/DI water. I have been struggling with high Nitrate levels in my tap water and thought RO/DI would be the best solution. I also thought that i could just mix 50/50 or so to bring down my Nitrate levels enough so I would not have to dose them and also not have to add back the minerals lost in the RO/DI process. 

It's all unfamiliar territory.

Any advice is GREATLY appreciated!


----------



## Edward (May 25, 2004)

http://www.aquaticplantcentral.com/forum/viewtopic.php?t=1153


----------



## Nystina (Nov 24, 2004)

Funny you replied to this topic Edward :wink: It was your thread that made me unsure (pretty advanced stuff here!)
http://www.aquaticplantcentral.com/forum/viewtopic.php?t=1437&highlight=ro+di+kh

From what i got from the other thread you just gave me, it really can work well either way, but i'm still unsure why my LFS is so against TDS and also the problems associated with raising KH in pure RO/DI water with, say, baking soda....


----------



## Edward (May 25, 2004)

Here is what I would do,
mix dry:
1.5 g CaSO4
1.0 g MgSO4

Dose 1/2 tsp per 100 l or so, until you read 20 ppm of Ca. This is the minimum Ca test kit Hagen can read. At this point you will have 20 ppm of Ca and 5 ppm of Mg, the ideal concentration to grow plants at a ratio of 4:1.
More is not better as this is already 4 dGH.

Because you need to inject CO2 your pH will be pushed down. We know that 30 ppm of CO2 is ideal, so here http://www.aquaticplantcentral.com/forum/viewtopic.php?t=2544 you can find what KH is needed to get pH of your choice. RO water doesn't have any KH. To increase the KH you need to use dry CaCO3. Dose slowly and wait 24 hours before testing it.

Baking soda works well to increase KH and dissolve fast but, leaves Na behind. This Na doesn't cause any problems as long as you keep changing water all the time. I prefer using a cleaner alternative CaCO3.

- TDS is an essential equipment to have when dealing with RO and soft water.
- The DI section I would remove because there is no benefit from using it, only a risk when one part of it runs out of charge then you will be getting an acid or a base depending on the product. 
- Mixing RO with tap? Not the best idea. Once you have the option to work with pure water from RO unit, you are in control, you can mix anything now, no reason to contaminate it again.

Edward


----------



## Nystina (Nov 24, 2004)

That helps immensely Edward!!! Just a couple more newb questions if you don't mind:



> Dose 1/2 tsp per 100 l or so,


 is that 100 Liters(i must double check to be sure)?

Also where is a good place to look for dry CaSO4 and MgSO4? That's ALL you add?? I have no idea what those are BTW :lol: (never took chemistry)

Thanks Again!


----------



## Edward (May 25, 2004)

> Dose 1/2 tsp per 100 l or so, ... is that 100 Liters(i must double check to be sure)?


Yes, liters.


> Also where is a good place to look for dry CaSO4 and MgSO4?


Check http://www.aquaticplantcentral.com/forum/viewforum.php?f=31 , http://www.aquaticplantcentral.com/forum/viewtopic.php?t=35, your Drug Store special order desk and yellow pages Chemical supplies.


> That's ALL you add??


This covers Ca, Mg and KH/pH. Another issue is NO3, PO4, K and TE (Trace Elements), http://www.aquaticplantcentral.com/forum/viewtopic.php?t=2418 .

Edward


----------



## TomE (Jul 24, 2004)

Edward said:


> Baking soda works well to increase KH and dissolve fast but, leaves Na behind. This Na doesn't cause any problems as long as you keep changing water all the time. I prefer using a cleaner alternative CaCO3.


Okay, I thought I had a good understanding to my tank. :shock: Okay, I normally use baking soda. But now I'm interested into look at CaCO3. Let me get this straight, If I use CaCO3. Ca will bind to the water and increase my KH. Will CO3 be absorb by the plants ? Also, Dosage of CaCO3 same as Baking soda?

Thanks, This post has a lot of great info.


----------



## JLudwig (Feb 16, 2004)

TomE said:


> Okay, I thought I had a good understanding to my tank. :shock: Okay, I normally use baking soda. But now I'm interested into look at CaCO3. Let me get this straight, If I use CaCO3. Ca will bind to the water and increase my KH. Will CO3 be absorb by the plants ? Also, Dosage of CaCO3 same as Baking soda?


No  The CO3-- is the "alkalinity" part of that chemical the Ca++ will help with general hardness. If your KH is low usually your GH is low too so CaCO3 kills two birds with one stone, but its not very soluable, thats the problem. The way around the soluability issue is to filter over it, crushed coral is CaCO3, very easy to put into a nylon stocking in the filter. But then you have the trouble of figuring out how much dissolved. If your plants aren't showing calcium deficiency dont change anything, the Na is harmless in the concentration we're talking about.

Jeff


----------



## Nystina (Nov 24, 2004)

I think i will try the dry fert route. I read your (Edward) post on your Perpetual Preservation System and i think i might try that out for a while. I cannot seem to find CaSO4 and MgSO4, so is baking soda a suitable replacement for your method? If so, are there anything i do different?

Thanks!


----------



## Edward (May 25, 2004)

GH is made of Ca and Mg, (CaSO4, MgSO4, CaCO3)
KH is made of CO3, (CaCO3, NaHCO3 soda)

CaCO3 is used to increase KH where RO or tap is too low, the same way as soda. CaCO3 makes water cloudy for few hours, dose over night. Ca will be available to plants and the CO3 (KH) portion will be taken by some plants in small quantities.

To increase:
Ca use CaSO4
Mg use MgSO4
KH use CaCO3 or NaHCO3 soda

Edward


----------



## Laith (Sep 4, 2004)

Just to clarify re the various options:

To raise ONLY GH: add a mixture of CaSO4 (or CaCl) and MgSO4
To raise ONLY KH: add NaHCO3 (sodium bicarbonate)
To raise BOTH GH and KH: add CaCO3

Personally, if I want to raise both GH and KH I use CaCl and MgSO4 to raise the GH and NaHCO3 to raise the KH. The reason being that I've found that CaCO3 takes forever to have any impact given its insolubility.


----------



## niko (Jan 28, 2004)

Laith,

Just to add to your last post:

Using CaCO3 requires time. After adding the dry powder to the tank you will not see an immediate increase of the KH. It seems that it takes a few days, not a few hours, to see the increase. You will actually see most of the powder just sitting in your tank without disolving for a few days anyway.

--Nikolay


----------



## plantbrain (Jan 23, 2004)

So why is it bad to mix RO with tap?
Why is the tap bad to begin with?

The high NO3 sounds like it's something else going on.
Even if you have 40ppm of NO3, changing 50% will add abiout 20ppm extra each week, I keep that level in my tanks and they grow great.
Plants will remove if you focus on their needs. If not, you will see a build up in nutrients, namely NO3 and to a lesser degree PO4.

Having tap with NO3 just means you don't have to add it via KNO3. You'd use K2SO4 instead after the water changes only.

Why take something out only to add it back again?
Edward suggest it's to keep the water clean and pure and to know what you are working with, sure, but you simply do not need that hassle to grow the plants and keep the fish, blending with tap is fine if you need to reduce the hardness.

Not sure why anyone would want to have to add GH and KH back again in a planted tank after removing it.

That is a huge hassle.
You do not gain anything plant health wise from it either.
I've done both for many years till I figured it out after using a wide range of tap waters and nutrients.

Plants don't care, your fish might do well with softer water though. 
I have super soft water again now and I hate it.

But will it hurt using pure 100% then adding the make up nutrients to RO and doing all that? No. Is it more work? You bet. Do you need to do it? Nope. Is it more "accurate"?, Yes, but do we need this accuracy to grow plants well, keep soft water fish? Nope.

Those are the basic questions you will want to ask and decide on.

RO water taste good though.

Regards, 
Tom Barr


----------



## plantbrain (Jan 23, 2004)

Nystina said:


> Hello everyone,
> I have been reading some posts on the use of RO/DI water and it's quite confusing.
> My questions are.... i've read that KH is a problem with RO/DI water, how do you address this and what should I be aware of?
> 
> ...


As far as high TDS, they are incorrect. The revese is more true than this statement. This is a myth. There area couple of plants that "appear" to do better, but out 300+ species, that's less than 1%. So if you want to generalize, I'd say plants pefer high GH/KH.

I would blend RO to get a KH of 3, GH of 3 or high for Altums.
After they fatten up, reduce the KH to 2 or so.
A KH of 2 works well.
I do 50-80% weekly water changes on the Altum tanks I have done and am doing with a KH of 3, they do quite well.

Happy plants = happy fish.

Regards, 
Tom Barr


----------



## Nystina (Nov 24, 2004)

Hehe... actually i don't keep altums  I'm afraid to. Just regular angelfish for me! But i do think they are the nicest looking fish i've seen.


----------



## plantbrain (Jan 23, 2004)

Well there's another question for you, why not keep them?
They are not terribly difficult.

Look good, better than Discus Wild discus are nice though....

Regards, 
Tom Barr


----------



## Raul-7 (Feb 4, 2004)

But if you're going to keep them, the best plan is to have a tank of at least 20" deep.


----------



## Nystina (Nov 24, 2004)

I have a 50gal Tall (20"), but they aren't easy to find, and i have too many fish right now anyway. :wink:


----------



## Jason Baliban (Feb 21, 2005)

I guess there is no perfect answer to KH/GH? What are some thoughts on this. It seems like a fairly small piece of the puzzle.....but as with anything else, nobody can give a solid reasoning for their thoughts on GH/KH. Will anyone venture to offer the "ideal" GH/KH levels? And more importantly.....a reason for there choices? I live where the water is uber hard......so i mix with RO/DI. My tank's water conditions are 4.5 KH and GH....but I dont know why this is good or bad?
Any thoughts?
jB


----------



## plantbrain (Jan 23, 2004)

I would say GH is a very wide range. 2-3 degrees or more up to 25?
I would say KH is also a very wide range. 0-20, 2-3 is better but if you can keep a safety margin at 1, that's fine, there is some arguement that a KH of 0 is bad, I sort of doubt it is.........even with CO2 is some cases. There are some backdoor ways to ensure safely using it and a KH of near zero.
But I find little issue with having 3KH also with any fish species. 

Ideal?

Perhaps
KH 3
GH 5

It's a huge target, you can pick, GH is a combo of Mg/Ca, both plant nutrients........so zero is no good......

Regards, 
Tom Barr


----------



## Rolo (May 12, 2004)

plantbrain said:


> ...there is some arguement that a KH of 0 is bad, I sort of doubt it is.........even with CO2 is some cases. There are some backdoor ways to ensure safely using it and a KH of near zero.


Tom, I'm interested in know about doing CO2 safely with a KH near 0.

I talked with someone who knows about the water parameters in Nagita (ADA HQ) and they told me the KH is 0-1, GH 2-3. Then there's the Aquasoil they use which could make it softer yet.

But interestingly the pH doesn't crash, even with injecting a lot of CO2 (and w/ no controllers). The pH bottoms out to 6.60 in the evenings, while you'd expect with a KH this low for pH to fall into the 5 range. The _speculation_ was that naturally soft water must have high stability - as opposed to "artificially" created soft water by RO.

Just curious to know if this ties into what you were saying.


----------



## shalu (Oct 1, 2004)

I have asked Tom that question before, I think he told me ph goes to 4-5. Fish were ok. So different from ADA setup. My guess is ADA substrate has some kind of buffer in effect.


----------



## Raul-7 (Feb 4, 2004)

Shalu, I've seen tests were fish could live in pH much lower than 5, it was closer to 2. And the main aspect of AquaSoil is it's buffering effect.

Rolo, I think the key is that Amano only injects C02 for 4-6 hours in correspondence to the MH illumination on his tanks. But I'm not sure if it's enough to keep the pH from crashing.


----------

