Co2, Ph, Kh question... - The Planted Tank Forum
 
LinkBack Thread Tools Display Modes
post #1 of 13 (permalink) Old 06-22-2005, 06:36 AM Thread Starter
Guest
 
PTrader: (0/0%)
Join Date: Feb 2005
Posts: 63
Co2, Ph, Kh question...

Im confused... This might sound stupid but as my Ph lowers is it possible that the Kh rises with it? Because i checked my ph and kh about a month ago and had a ph of around 7.2 - 7.3 witha kh of 10 and last week and got a reading of around 7.1 - 7.0 with a kh of 12 and jus teated my water today and got a ph of 7.0 and a kh of 13 which gives me a Co2 of 39 so does the Kh go up when the ph decreases and more co2 is added or could me kh been tested wrong?
Aj86 is offline  
Sponsored Links
Advertisement
 
post #2 of 13 (permalink) Old 06-22-2005, 02:55 PM
BSS
Guest
 
PTrader: (12/100%)
Join Date: Sep 2004
Posts: 1,600
I don't believe that KH should normally fluctuate. There are times when the source tap water will change in areas during different times of the years. But, if you haven't added any water, and the KH is changing that much, then something is wrong. Do you have driftwood or shells or something in your tank that could be leaching/dissolving over time?

A former 29g of mine used to have slowly dropping KH levels. I didn't think it was a problem initially, but one day my PH crashed and I found my KH at <1. I eventually tracked it to 'toxic' driftwood. So, I'd do some investigating and not ignore this one!

Brian.
BSS is offline  
post #3 of 13 (permalink) Old 06-22-2005, 03:33 PM
Guest
 
PTrader: (0/0%)
Join Date: Mar 2004
Posts: 228
Well I sure don't know what is causing it (only guess is my eco-complete), but my tap KH is ~1.5 and this am my tank KH is at 7.7 ppm. The ap test shows it between 7-8 and the Salifert test (more accurate imo) shows it at 7.7 . In fact just to show you how it has risen over the last week

6-16 3-4 ap test
6-17 4-5 ap test
6-17 5.1 Salifert test
6-18 5-6 ap test
6-19 5-6 ap test
6-20 7-8 ap test
6-21 7-8 ap test
6-21 7-8 ap test
6-21 7.7 Salifert test.

After wc it drops. Ill post back tomorrow after my wc.
mikey is offline  
 
post #4 of 13 (permalink) Old 06-22-2005, 04:10 PM
Guest
 
PTrader: (0/0%)
Join Date: Nov 2003
Posts: 2,165
Mikey, it looks like you're talking about dKh one second, and ppm the next. You have to convert dKh to ppm...they are interchanagable like ppm and mg/L

The most common reason Kh rises in the tank is that you have some evaporation, which only removes H2O, not Kh. Even if you don't top-off to replace this between water changes, the trend will lead you to slowly raise Kh, especially if you already have moderately hard water (like me).

Thus I always recommend 50% water changes weekly for planted tanks to reset nutrients, and then occasionally I personally will do 75% changes to dilute my Kh back down to tap levels. My tap is about 9dKh, but my tank has reached 14dKh when I got lazy with water changes and just did top-offs for a few weeks.
malkore is offline  
post #5 of 13 (permalink) Old 06-22-2005, 04:37 PM
Planted Tank Guru
 
scolley's Avatar
 
PTrader: (11/100%)
Join Date: Apr 2004
Location: connecticut
Posts: 3,279
Quote:
Originally Posted by mikey
Well I sure don't know what is causing it (only guess is my eco-complete),
Mikey - IMO this is a bit off topic on aj86's thread, but if that Eco-Complete is new (less than 9 months old), I'd dig some out of the tank and run tests on it. I don't know if you've seen the threads on the recent rash of corrupted EC, but it's worth doing a search on.

Put a good bit of EC in a cup, just barely covered with water from the tank. Also get a cup of tank water with no EC in it. Let them sit and test them both in a few days. If the KH or GH in the EC water is higher, you've found your culprit.

Steve - 33g reef and a 180g planted in need of a re-scape.
scolley is offline  
post #6 of 13 (permalink) Old 06-22-2005, 04:49 PM
Guest
 
PTrader: (0/0%)
Join Date: Mar 2004
Posts: 228
Aj86 .... sorry if I got your thread off track but maybe some of these answers are on-track for you?

Malkore ... your right .... I meant dKH all the time but just goofed with ppm. I have had about 2 gal evap since last saturday's wc (~ 5%) with no top off. Ill start to top off.

Steve... Ill do the test and let you know.
mikey is offline  
post #7 of 13 (permalink) Old 06-22-2005, 05:30 PM
BSS
Guest
 
PTrader: (12/100%)
Join Date: Sep 2004
Posts: 1,600
Quote:
Originally Posted by malkore
My tap is about 9dKh, but my tank has reached 14dKh when I got lazy with water changes and just did top-offs for a few weeks.
I certainly would have guessed some amount of KH rise with top offs. But 5dKh is a bit surprising to me. I guess if you have 10% evap per week and top off every week, after 5 weeks you could see a 50% increase in dKh.

I guess the initial post does state that this is over the course of a month...
BSS is offline  
post #8 of 13 (permalink) Old 06-22-2005, 05:41 PM
Algae Grower
 
victri's Avatar
 
PTrader: (0/0%)
Join Date: Dec 2003
Location: NC
Posts: 46
Do you have any rocks in there? There might be something leaking carbonates, causing this rise.

Over a course of a month, it might be possible though, if 2 gallons evaporate every 4 days, that's about 15 gallons topped up in a month!

Vic
-------------------------------------------------

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
victri is offline  
post #9 of 13 (permalink) Old 06-23-2005, 12:03 AM Thread Starter
Guest
 
PTrader: (0/0%)
Join Date: Feb 2005
Posts: 63
Thanx for all your help guys... I do have driftwood in there but it has been in there for almost a year i think i also do have sandstone rocks which have been in there jus as long as the wood but i have just recently added slate which i added after my first kh test could that be the cause of the rise? Also about the evapouration im not quite sure what you mean about that but i hardly have any evapouration the tanks are the same level from when after i fill it to before my next water change...
Aj86 is offline  
post #10 of 13 (permalink) Old 06-24-2005, 02:16 AM
Guest
 
PTrader: (0/0%)
Join Date: Jul 2002
Posts: 160
IMO the result of your KH test kit is wrong. There is another acid, either from nitrification, driftwood, peat, etc. that is being titrated with the bicarbonate in your water giving you a false higher reading for KH than is the case. Let's look closely at your postings.

Your pH was 7.3 with a KH of 10 which would indicate 15 ppm of CO2.

Now, without increasing your CO2 your pH has dropped slightly to 7.0 but your KH "seems" to have risen to 13 which would indicate CO2 of 39 ppm....that's not possible unless you deliberately increased your CO2 injection over two fold.

In reality your tank water contains another acid, this has suppressed the pH slightly and interferes with the simple KH test kit titration...that is why we can't filter with peat and why we can't use a phosphate buffer...the charts depend on having a bicarbonate/carbonate only buffer, any other large amount of acid or base interferes with the accuracy of the chart.

You can take Malkore's advice and step up the quantity and frequency of your water changes and this problem will be self correcting as your tank water begins to return to the same conditions as your tap water.

If your unconvinced about my diagnosis you can perform a small experiment. Remove a cup or two of water from your tank. Aerate that water overnight in a bowl and then take a pH and KH reading. If the results don't reflect 2-5 ppm of ambient CO2 then you know you have KH test kit interference.
Steve Hampton is offline  
post #11 of 13 (permalink) Old 06-24-2005, 04:19 AM Thread Starter
Guest
 
PTrader: (0/0%)
Join Date: Feb 2005
Posts: 63
Thanx for your reply steve i completly forgot to add this with the rise in the co2 when i tested the ph and kh the first time i was only adding little co2 because i was playing around with the mixtures now i think i have got the mixture right and thats when i tested the ph and kh the last time and got 39ppm of co2...
Aj86 is offline  
post #12 of 13 (permalink) Old 06-26-2005, 12:09 PM Thread Starter
Guest
 
PTrader: (0/0%)
Join Date: Feb 2005
Posts: 63
bump......
Aj86 is offline  
post #13 of 13 (permalink) Old 06-26-2005, 04:09 PM
Wannabe Guru
 
lumpyfunk's Avatar
 
PTrader: (32/100%)
Join Date: Dec 2004
Location: Prior Lake, MN (Twin Cities)
Posts: 1,602
Quote:
Originally Posted by Aj86
Thanx for your reply steve i completly forgot to add this with the rise in the co2 when i tested the ph and kh the first time i was only adding little co2 because i was playing around with the mixtures now i think i have got the mixture right and thats when i tested the ph and kh the last time and got 39ppm of co2...
My guess is that you have something that is leaching KH into your tank as CO2 levels rise the ph is lowered because you are adding carbonic acid into your water, this in turn speeds up the disolving of solids that effectivly increase your KH which should raise your ph.

IMO if you are using DIY you should be fine, but if you have a PH controler this can become a visious cycle that ends with dead fish.
lumpyfunk 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