This site is supported by the advertisements on it, please disable your AdBlocker so we can continue to provide you with the quality content you expect.
  1. This site uses cookies. By continuing to use this site, you are agreeing to our use of cookies. Learn More.
  2. We are after as many aquarium plant images that we can get, doing so will assist us in completing the aquarium plant database.

    https://barrreport.com/threads/aquatic-plant-images-wanted.14374/
    Dismiss Notice

KH/pH mystery?

Discussion in 'CO2 Enrichment' started by AmirM, Oct 4, 2007.

  1. AmirM

    AmirM Prolific Poster

    Joined:
    Sep 26, 2007
    Messages:
    40
    Likes Received:
    0
    Local Time:
    7:21 PM
    Hello Everyody,

    I'm new at this forum and very glad I reached this website, looks great and very scientific. I'm new to planted aquarium and will appreciate your advice.
    I read a lot in the articles section about pH/KH and CO2 calculations but:
    I measured pH of 6.4 KH of 7d and according to the table- that should mean around 80ppm CO2- the mystery is that the fish seem absolutely fine!
    Can anyone guess what's going on?

    Is it possible that the under-gravel fertilizer is somehow influencing the readings?
    The fertilizer is a mixture made in a local shop (peat moss, humus, pumice....)

    The last time I tried to raise the CO2 flow- I had two SAE deaths, and I really try to avoid these unnecessary deaths.

    Thanks for your advice
    Amir
    ________
    Percocet rehab advice
     
    #1 AmirM, Oct 4, 2007
    Last edited by a moderator: May 2, 2011
  2. ceg4048

    ceg4048 Lifetime Charter Member
    Lifetime Member

    Joined:
    Mar 21, 2005
    Messages:
    240
    Likes Received:
    0
    Local Time:
    7:21 PM
    Hi Amir,
    The pH/kH/CO2 relationship only ever valid when CO2 is the only source of acid in the water. If you have acids or alkaline substances in the water from other sources such as Peat or Phosphates these substances will drive the pH as well as the CO2 therefore measuring the tank water is never a good idea. If you search on the forum you will find references to the use of a drop checker an instead of using tank water it's best to use a sample of distilled water that is completely free of contaminants and has a known kH.

    Humus and Peat are known acidic sources, therefore these components along with many other substances in tank water immediately invalidate the pH/kH/CO2 relationship and the chart or formula is useless.

    Cheers,
     
  3. AmirM

    AmirM Prolific Poster

    Joined:
    Sep 26, 2007
    Messages:
    40
    Likes Received:
    0
    Local Time:
    7:21 PM
    Thanks for the quick and helpful reply
    I will use Distilled water (dKH 4) in the drop checker.

    Another related question is: what is the general rate that CO2 is entering/leaving the water?
    If I try to increase slowly the CO2 inflow- will it be possible to prevent deaths once stress is noted among the fish?
    Thanks
    Amir
    ________
    PRILOSEC LAWYERS
     
    #3 AmirM, Oct 4, 2007
    Last edited by a moderator: May 2, 2011
  4. tcomfort

    tcomfort Junior Poster

    Joined:
    Jul 24, 2007
    Messages:
    26
    Likes Received:
    0
    Local Time:
    7:21 PM
    Another problem with the pH/KH/CO2 relationship is that it is very "twitchy." Relatively small errors in the measurement of the pH and KH (very easy to have with hobbyist test kits) can lead to much larger errors in the supposed amount of CO2. You didn't actually have 80 ppm of CO2, something else was going on.

    The rate of CO2 going in and out of solution is extremely variable depending on lost of factors, such as water-to-air surface area, water movement, efficiency of the CO2 reactor, and so on. I've never really liked the "stress the fish and then back off a little" method, just because it is easy to very slowly increase your bubble rate until your drop checker goes green. 30 ppm of CO2 won't stress the fish.
     
  5. VaughnH

    VaughnH Lifetime Charter Member
    Lifetime Member

    Joined:
    Jan 24, 2005
    Messages:
    3,010
    Likes Received:
    87
    Local Time:
    7:21 PM
    Even with a drop checker, with 4 dKH distilled water in it, you can overstress the fish. The problem is determining the color of the indicator. You want it to be green to have 30 ppm, but if it is yellowish green you wil have 40+ ppm, which is too much for the fish. And, not all fish react the same to CO2. I find my guppies are the most sensitive fish that I have, while my lambchop rasboras don't seem to mind the higher amounts. If you can keep BBA from starting, using a lower amount of CO2 is much better, but that requires that the water circulation be very, very good in the tank, so even the areas with less water flow get enough CO2.
     
  6. Tom Barr

    Tom Barr Founder
    Staff Member Administrator

    Joined:
    Jan 23, 2005
    Messages:
    18,648
    Likes Received:
    556
    Local Time:
    7:21 PM
    Adding further to this issue:

    Light levels, nutrient limitations, plant biomass as well as species type etc can influence CO2 demand from plants.

    Some might be okay with 15ppm of CO2 at 3 w/gal with a rug of HC in a well scaped iwugamiscape, whereas someone with a well lit dutch scape might require 30ppm etc.

    While these may be minimum levels, the maximum levels tend to be defined by the fish, which if you set up the system correctly, can be at 30ppm, just because you happen to get away with less, does not mean you apply it to every case.

    Some do so without consideration about plant biomass, light, and nutrients etc. Do not fall into that trap.

    When addrssing CO2, it is likely best to eyeball how the plants grow best, but when you are sure that the plant biomass is consisent, flow, cleaned filters are present, good water changes, stable feeding, stable dosing of non limiting levels, then test the CO2.

    The goal is use a combo, use all the methods available to you to measure CO2.

    1.Plants growth/health/pearling/O2 levels
    2. pH KH levels.........these maybe relative levels, level which you know work for your particular system having gone through the above routines.
    3. More precise measures of pH/KH- drop checker is good here, however, thesre are some trade offs here, one is color resolution, some folks are color blind...............they cannot use this method without help.
    4. pH drop checker take about 2 hours or so to equilibrate to the actual conditions in the tank.............

    A tank can run "dry" of O2 in less than 1 hour.............

    5. You can try various membranes and CO2 reference points and make a pH/KH reference pH probe+ a membrane, this a DIY project and getting a good bubble free seal, using a flat tipped pH probe are required.
    You can buy a CO2 reference probe set up for about 500-700$ or so.

    Not a small amount.

    6. You may use very large back to back water changes to remove any peat or tannins in the tank water to get a reference measure of pH.

    So you remove all the acids and replace with tap, then measure pH/KH and use that reference. as a baseline. You may also use RO water + baking soda to get a KH refernce if you suspect the tap water having non carbonate alklalinity as well.

    From there, as long as the CO2 rate added is the same, and the plant biomass, KH, nutrients, light are similar, then the movement of the pH due to tap, due to tannins from wood etc, are not due to CO2.

    So say the tank RO/Baking soda 90% water(2-3days in a row of this) changes is a pH of 6.4.

    After awhile the tannins or peat drop it to 5.8.

    You know that the CO2 is 30ppm at the reference, the new 5.8 is also at 30ppm as well, even though the pH/KH table now says it's 130ppm, but fish are fine and so are plants etc

    Such back door common sense approaches allow a lot more used input than banter, they offer solutions and answers.

    Seeing which trade offs work well for you is a key here.

    I find that the plants are the best test kits as well as algae.
    This simple method has never failed me.

    I do test later............with a good hypothesis and decent method to test to see if it's true. But I do not test merely to monitor, I test on purpose driven question which teaches a lot more.

    This method wor much better and reduces the work involved and answers questions rather than repeating history over and over again and the same associated myths.

    Reinventing the wheel gets old:rolleyes:

    I think many can agree on that.
    The drop checker is not reinventing, yet the idea is very old, at least 25 years old. Adding the KH ref solution is somewhat new. Combining good justitifications for them(This part maybe new) is a step closer to being better for the future hobbyists.

    Regards,
    Tom Barr
     
  7. AmirM

    AmirM Prolific Poster

    Joined:
    Sep 26, 2007
    Messages:
    40
    Likes Received:
    0
    Local Time:
    7:21 PM
    Thanks for all the advices

    I will work on the 4dKH solution for the drop checker and try to use this together with watching the plants and algae closely.
    Right now there is a nice rate of pearling, but this is not an objective observation as I'm not experienced in high-tech planted aquaria.....
    I will post a detailed description of my tank's setup and will appreciate your advices.
    Once again- I really enjoy this website and find it highly evidence based and professional.
    Thanks
    Amir
    ________
    NEW JERSEY MEDICAL MARIJUANA DISPENSARY
     
    #7 AmirM, Oct 6, 2007
    Last edited by a moderator: May 2, 2011
Loading...

Share This Page