CO2, KH, PH and dying plants

R

robson

AC Members
Jul 5, 2005
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Hi,

I have read many articles on this forum regarding water hardness and PH, but I'm still missing bits to put whole puzzle together.
I have 300L tank and my water in the tank is PH=8.2 KH=130ppm and GH 260ppm. When I bought the tank I also bought a pressurized Co2 system and I expected to see the plants to grow like mad, but it didn't happen. I set my bubble counter to 33 bubbles per minute, but according the table showing the dependency between KH, PH and level of CO2 the is almost no CO2 and therefore my plants don't grow as I expected. The CO2 system is running in the tank for almost 2 months. I need your help. What should I do to increase the level of CO2?
If more CO2 were injected in a tank, would it change PH, KH, or both? I placed the CO2 counter at the bottom of the tank near the filter output tube.
Is it a right place, or it's completely wrong? I expected that filter current will distribute the CO2 around the tank, but maybe it does the opposite.

I forgot to describe the lighting I have which could by my problem as well. I'm running the tank with 2 fluorescent tubes
Aqua-glo 38W. Is it enough for such tank?

Thank you in advance for any suggestion, comment, or help.
 
You're running at about 1 wpg, which is very low light. CO2 won't help you much at this point. You should probably double your lighting, at the least. What kind of filter do you have? And, CO2 will affect pH, but not KH.
 
At the bubble rate you report, there is something wrong somewhere for you to be getting only 1ppm/CO2.
Injection will help, even at the low WPG that you mention and as mentioned above that should be increased to at least 2WPG for better results.....preferably CF lighting.
For better advice, knowing the way you are injecting, filter type and height of the tank is necessary.

Len
 
How is it you are diffusing the CO2? How is it "spread around" the tank? If the bubble is floating up and just being pushed a little, it isn't dissolving into the water. Try a search for "reactor" or "diffuser" to get some ideas of the various ways this is done.
 
Also if you can include the lighting period or time. Also what kind of substrate, although that is not so important and what ferts you are using.
 
Just so we're in your measurement world....


You are looking to try to get around 150-160 watts for your tank. In otherwords you are going to need about .5 watt per liter to get the "2 watts per gallon" amount that people are speaking of. The taller the tank is the more you end up needing though. If your tank is one of the taller types you will need closer to 3 watts per gallon or .75 watts to get some plants going good. Plants that need bright light will need more in a bigger taller tank.

In otherwords... tanks like yours is the equivalent of about 75-80 US gallons. If this is about the normal height for tanks near its size medium light plants will do ok at 2-2.5 watts per gallon (.5+ watt per liter) ratio. If you want HIGH light plants then you need 3-3.5 watts per gallon (.75+ watt per liter)

Anything lower and only the strongest plants will survive. If your pH is high and your kH is high plants will likely wither up and die... In your case the pH is a bit high and the kH is about "normal to low" this is the equivalent of about 7.28 degrees German Kalkwasser hardness...

ROUGHLY if there are no other weird buffers and good clean pure water with little to no additives besides things mentioned at approximately 70-75 degree temperature result in a 1.1-1.3 ppm CO2 ratio. This is about as low as "non-existant" you can get injecting CO2. Your mixture is not working and you will need to find a better mixing technique and way to inject more into it. Bubble counters for larger size tanks are virtually useless IMO and you need to look at electronic controllers and solenoids to control the flow of gas.

Once you increase your light to around 150-220 watts you will need to inject enough CO2 that it will likely drop your pH down to around 7.0 from the current 8.2 unless this is by a chemical which locks in an 8.2 pH level. If you are not using one that does that this will give you a 20ppm CO2 and your plants will go insane with growth...

If you need to keep it around 8.2 pH then you will have to inject a LOT more CO2 and buffer the tank upwards with a non kH involving buffer. In these circumstances the online charts and calculator resources are unreliable and death is likely due to too much Co2 suffocating the fish. Automated controllers also likely will not work well since you may end up with a chemically created pH that does not shift with the introduction of CO2 the same way as plain carbonate buffered tank.
 
lbritish said:
If you need to keep it around 8.2 pH then you will have to inject a LOT more CO2 and buffer the tank upwards with a non kH involving buffer. In these circumstances the online charts and calculator resources are unreliable and death is likely due to too much Co2 suffocating the fish. Automated controllers also likely will not work well since you may end up with a chemically created pH that does not shift with the introduction of CO2 the same way as plain carbonate buffered tank.
Click to expand...

I don't want to sound rude, but where do you get that information from.
1# increase the Co2 input and the ph will go down.
2# how do you increase the buffers without affecting the kh, buffers are carbonates or bi-carbonates which will dirrectly affect the kh.
 
I do not understand how high pH and high KH will cause plants to shrivel up and die? Are you saying that the Rift Lakes are plant-free? Sorry but I think is way off base.

I am also at total loss as to why a non-carbonate buffer is needed/desired? Exactly what purpose is this to serve other than to make CO2 all but impossible to read? Sounds much like shooting yourself in the foot to me.
 
Thank you to everybody replied.

It's apparent, that there is a lack of light in my tank. I will fix it. Regarding the PH and CO2 a supply all information you requested to be able to help me.

Filter - I run internal filter supplied with Juwel Rio 300 aqaurium
The tank is 62 cm tall.
Way CO2 is injected :
setbis300ohne.gif

The picture shows what equipment I'm using. Hopefully it makes it clearer.

Period the light is on: 14 hours
I have no plant-substrate. I'm using just gravel size appox. 5mm
Fertilizer I started to use just last week and I don't remember the make from the top of my head.

Once more thank you to all of you and I hope that with the information I gave you will be able to help me to sort out the mess in my tank.
 
Looking at that set up you should be getting plenty of Co2 in there, do you have a lot of surface movement? Also what are testing your ph with, the reading it is giving you could be wrong.
Btw for a high light tank you could use up to 1w/ per/ L which would translate to about 4w/ per/ g. If you are going to use that amount of light make sure you use fast growing or high light plants.
 
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