PH too high after RO/DI - The Planted Tank Forum
 
LinkBack Thread Tools Display Modes
post #1 of 7 (permalink) Old 01-28-2009, 12:41 AM Thread Starter
Algae Grower
 
PTrader: (0/0%)
Join Date: Jan 2009
Location: Chicago, IL
Posts: 144
PH too high after RO/DI

What would cause my PH to read 7.4 after RO/DI filtration? GH & KH tested at zero (as expected). I thought pure water would have a neutral PH of 7.0.

In fact, I get a reading of 7.4 when I test unfiltered tap water as well.
ExReefer is offline  
Sponsored Links
Advertisement
 
post #2 of 7 (permalink) Old 01-28-2009, 12:53 AM
Planted Tank Enthusiast
 
metageologist's Avatar
 
PTrader: (0/0%)
Join Date: Jan 2008
Location: Mannsville NY
Posts: 794
what are you testing with?

if you are not using a calibrated PH probe you are within the error percentage of any non calibrated equipment
metageologist is offline  
post #3 of 7 (permalink) Old 01-28-2009, 01:13 AM Thread Starter
Algae Grower
 
PTrader: (0/0%)
Join Date: Jan 2009
Location: Chicago, IL
Posts: 144
Quote:
Originally Posted by metageologist View Post
what are you testing with?

if you are not using a calibrated PH probe you are within the error percentage of any non calibrated equipment
API freshwater test kit. I used the API kits to test the GH and KH as well.

You might be right about some error. 0.4 is not much. What's strange is my plant tank water PH is also 7.4 but with a KH level at 5 deg. That would mean my CO2 level is only about 7.5ppm. That CO2 level seems low considering my plants are pearling during my 4hr. high light boost. Assuming the PH is probably closer to 7.0 in my plant tank and with a KH of 5, that puts the CO2 at 15ppm, which is pretty good and would explain the plants doing so well under high light.

I only bothered to test because I'm trying to decide if I want to start using all tap water in my plant tank. I originally just wanted to know my tap water KH and GH readings. My tap water GH - 10, KH - 7. That's higher that I would like, but should be fine for most plants.


If my RO/DI filtered water had zero readings for GH and KH, should I assume it is working properly and my PH is really 7.0?
ExReefer is offline  
 
post #4 of 7 (permalink) Old 01-28-2009, 03:06 AM
Planted Tank Guru
 
PTrader: (84/100%)
Join Date: Dec 2005
Location: Sacramento, CA
Posts: 21,012
The best thing to do is ignore the pH. Also, zero GH is a bad idea for a planted tank. Plants need some calcium and magnesium, so some GH is very desirable. If you are not adding any CO2 to the water, the amount in the water a day or two after filling it with tap water will be somewhere between about .5 and 5 ppm. This would be the amount in the water that would be in equilibrium with whatever is in air in the room with the tank. I think you would do very well just using tap water, not RO/DI water.

Hoppy
Hoppy is offline  
post #5 of 7 (permalink) Old 01-28-2009, 01:19 PM Thread Starter
Algae Grower
 
PTrader: (0/0%)
Join Date: Jan 2009
Location: Chicago, IL
Posts: 144
I think the Eco Complete substrate must have raised the KH & GH because I used 100% RO water in my 75 g. tank and the water tested at KH 5 and GH 6. I don't know what else it could be.

Anyway, I'm going to use tap water going foward and keep the RO water for my apisto tanks. This sure is going to make water changes easier.

I've read that I can simply add untreated tap water straight into the aquarium and then add some tap water treatment product to the tank afterwards. Is there any concern with this considering I'll be changing 50% of the water at times? Tap water contains harmful pollutants for fish.
ExReefer is offline  
post #6 of 7 (permalink) Old 01-28-2009, 03:49 PM
Planted Tank Enthusiast
 
houstonhobby's Avatar
 
PTrader: (3/100%)
Join Date: Dec 2008
Location: Houston
Posts: 612
ExReefer,

I agree that the Eco Complete is probably raising your KH and GH. I have a fairly new tank with Eco Complete and some other substrates that are supposed to be neutral, I use nothing but RO water, and the GH and KH continue to climb.

However, I'm not upset because zero GH and zero KH are both bad things. I use RO primarily because I don't trust the local tap water, having lost a bunch of fish that way, and I want to start with the purest water I can find. If it needs minerals you can always add them later, from pure sources.

Thanks,
Rod
houstonhobby is offline  
post #7 of 7 (permalink) Old 01-28-2009, 04:08 PM
Planted Tank Guru
 
PTrader: (84/100%)
Join Date: Dec 2005
Location: Sacramento, CA
Posts: 21,012
Quote:
Originally Posted by ExReefer View Post
I think the Eco Complete substrate must have raised the KH & GH because I used 100% RO water in my 75 g. tank and the water tested at KH 5 and GH 6. I don't know what else it could be.

Anyway, I'm going to use tap water going foward and keep the RO water for my apisto tanks. This sure is going to make water changes easier.

I've read that I can simply add untreated tap water straight into the aquarium and then add some tap water treatment product to the tank afterwards. Is there any concern with this considering I'll be changing 50% of the water at times? Tap water contains harmful pollutants for fish.
You drink that water, I assume? If not, at least you could do so safely. The only harmful stuff in tap water is chlorine or chloramine, added to avoid bacteria growing in the water, and Prime or another dechlorinator will take care of that. Most of us who use the Estimative Index method of fertilizing are replacing 50% of the water every week, normally with plain tap water, usually adding Prime to the water left in the tank before adding the tap water. Don't forget that our fish normally live in water we wouldn't dream of drinking.

Hoppy
Hoppy is offline  
Reply

Tags
None

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the The Planted Tank Forum forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:
OR

Log-in










Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode



Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome