RODI test results

[Coyne]

I received and set up my first RODI unit today. After letting it run for a bit and making sure there were no leaks, I went about testing the water so that I could compare it to my tap water and make sure everything is working.

Tap water (with 24 hr aeration)
pH: 8.6
KH: 17 (304ppm)
GH: 15 (268ppm)
TDS: 561

RODI water (no aeration)
pH: 7
KH: 0
GH: 0
TDS: 0

Im assuming that this is exactly what I want, but I wanted to check in with forum folk and be extra sure. The one thing that threw me was that, while conducting the KH and GH tests, the water never really turned any color. It just sort of stayed clear. There may have been the slightest of yellow and orange tinges to the water after one drop each, but I would ultimately describe the color as clear. Is this typical? Does the absence of everything (but H2O) confuse the KH and GH tests?

 

[dalto]

The GH and KH don't really work below a certain value. At least, I am not capable of reading them.

Also, you have some seriously hard water

 

[Coyne]

I know, right? Hence the RODI system.

 

[J.Mcpeak]

Those tests are perfect. Lots of zeroes and neutral.

Exactly the same as everybody.

I think the reagents need an amount of GH or Kh to react, hence the very pale single drop to stop test result. You will know 14 drops is double dark!

Be aware that the pH will drop over night to around 4 or 5 on RO water.

I deal with hard water too. Are you planning to just cut or remineralise?

 

[Coyne]

I deal with hard water too. Are you planning to just cut or remineralise?

I'm still trying to determine that. My first plan is to cut in some tap water. Im going to play around with some ratios tonight or tomorrow to see if I can get the results I want. That is to say, enough buffering capacity to stabilize the pH while keeping the pH as close to neutral as I can. If I can't get the results I want, then I may look into a product like Seachems Neutral Regulator or something similar. I think the Neutral Regulator isn't suggested for planted aquariums though.
I'm open to suggestions. I still need to get a 55 gallon container and a water pump.... so I'm not in a huge rush. My fish have been dealing with the liquid rock that comes out of my tap for almost 2 years now, so they can wait a little longer.

 

[Coyne]

Boy, you were right about the pH drop. I decided to test it after you mentioned this and, after sitting for about 24 hrs, its now at pH 6 (or lower, since my test bottoms out at 6).

I figured it would drop in an aquarium setting since it would be exposed to organic decay and there are no buffers to keep it stable. However, I did not know it would drop while just sitting in a bucket for a day.

Im going to keep this in mind while Im working out my RODI Water to Tap Water ratios. Im going to mix, let it set for an hour, test it, let it sit for another 23 hours and then test it again to see if there's any change.

My first attempt is with a 4:1 ratio.
pH 7.4
KH 4
GH 5
TDS 130

I'll see if there's a pH change tomorrow night, but this seems pretty ok to me. Maybe a touch more buffering would be good. I think I'll feel better if I can get the KH to 6. I'll have to try a 3:1 and a 3.5:1 mix and see where they land.

 

[thrak76]

Is that 4:1 RO/DI water to tap water, or reversed?

 

[Coyne]

4 parts RODI water and 1 part tap water

 

[thrak76]

I have similar (well) water to you, and I'm on the other side of the lake.

 

[Coyne]

Its my understanding that Lake Michigan plays a big part on why the pH and Hardness is so high in the surrounding areas. I don't know why exactly, or if its just Lake Michigan or all the great lakes that have this effect.

 

[thrak76]

Liquid rock.

I'm slowly transitioning to an African cichlid tank. Perfect water for that!

 

[Coyne]

I have plans to set up a 90 gallon sometime in the future and I may go the African Cichlid route as well. I'll have to see how manageable the PWCs are once I get all the kinks ironed out with this RODI set up. As it stands, a 55 gallon container will give me enough water to do weekly 50% PWCs on all of my current tanks. If I add a 90 gallon to that, then I'll have to pretty much refill the container again.

 

[thrak76]

I tried for a few years to maintain a planted tank with this water, and it was... difficult. I'll try again some time, but not until I can set up an RO/DI system. I've been transitioning for like 3 years now! I can't bring myself to rehome any fish, so until my show fish kick the bucket, I'm keeping the community tank.

I can't wait for an African cichlid tank though!

 

[dalto]

I tried for a few years to maintain a planted tank with this water, and it was... difficult. I'll try again some time, but not until I can set up an RO/DI system. I've been transitioning for like 3 years now! I can't bring myself to rehome any fish, so until my show fish kick the bucket, I'm keeping the community tank.

Maybe I am missing something but it seems like the obvious solution here would not be to re-home the fish, it would be to add another tank.

 

[thrak76]

Maybe I am missing something but it seems like the obvious solution here would not be to re-home the fish, it would be to add another tank.

Lol!

Believe me, I have tanks to spare! I've been through MTS and back!

However, my largest is the 75g and really the only one suitable for a nice colony. I suppose I could start growing them out in a 40b.... hmmm....

Really the main reason for not adding more tanks is a 3-year-old kid and a 3-month-old. That's another full time job!

 

[PNWaquarist]

Boy, you were right about the pH drop. I decided to test it after you mentioned this and, after sitting for about 24 hrs, its now at pH 6 (or lower, since my test bottoms out at 6).



I figured it would drop in an aquarium setting since it would be exposed to organic decay and there are no buffers to keep it stable. However, I did not know it would drop while just sitting in a bucket for a day.

The pH drop you're seeing is due to atmospheric carbon dioxide dissolving into the water. When it reaches equilibrium, the pH will be about 5.5.

You'll need to add baking soda or some other buffering agent before adding this water to an aquarium.



Sent from my iPhone using Aquarium Advice

 

[Coyne]

yup

 

[J.Mcpeak]

I use nt labs, GH+minerals and a Kh buffer from the same company.
Cutting with tap is fine, I did that for years, if you use lots of water it is cheaper to use powders as you still need to treat the tap water component of your mix, dechlorinate products work out much more expensive long term. It's a new thing for me which I only started earlier this year.

+1 on atmospheric C02 acidifying RO water. I've said exactly that on a few posts relating to RO water.

Kh buffer is the simplest way to increase Kh. It is so cheap you may as well use it. I think it's better for your system over baking soda but that's my opinion based on various articles I have read.

 

[Coyne]

I could be wrong about this, and I was still planning on treating the water with Prime to be on the safe side, but isnt the chlorine removed during the RO/DI process?

Edit: Just now saw that you were referring to the tap water.
Im pretty sure that the chlorine will just gas off after a day or two anyways, but its probably still better to be safe.

 

[PNWaquarist]

Lots of municipalities add chloramine to the tap water as well, which is not volatile. You'll need Prime to get rid of it.