CO2, KH, PH and dying plants

[robson]

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.

[mrakins]

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.

[djlen]

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

[beviking]

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.

[ashdavid]

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.

[lbritish]

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.

[ashdavid]

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.

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.

[RTR]

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.

[robson]

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 : http://www.aquamas.de/Bilder/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.

[ashdavid]

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.

[djlen]

Based on the information you've supplied, you are either gassing off CO2 in some way(surface agitation) or you're testing pH/kH is faulty.
If you intend to upgrade your lighting, I suggest that you go into the 2 - 2.5 wpg (CF) area, with a system that will allow you to add-on more light as you learn how to balance your tank. Take it slowly, rather than jumping into the 4wpg range.

Len

[robson]

For PH and KH measurement I'm using Hagen test kit. It could be that I didn't match the colour perfectly so PH could be down to PH=8, or theoretically 7.8, but not less.

Regarding a surface movement I can say that I have an internal filter that is creating some water movement and also an air stone, which can be considered that it disturbs the surface as well.

What should I do to minimise the surface movement? Should I increase the bubble rate? For how long would I need to leave the filter and air stone turned off to see the PH change and to prove that the problem is the surface movement?

I'm definitely going to upgrade the lighting in near future, just I have get some finance for that, because as you know the good lights are quite expensive.

[ashdavid]

Get rid of that air stone !, that is your problem, if you are concerned about oxygen in the water an air stone wont help you will get much more oxygen into the water column with healthy plants. An air stone is good for gas exchange which means you are getting rid of a lot of your co2 that you have just put in the tank.

[ashdavid]

Get rid of that air stone !, that is your problem, if you are concerned about oxygen in the water an air stone wont help you will get much more oxygen into the water column with healthy plants. An air stone is good for gas exchange which means you are getting rid of a lot of your co2 that you have just put in the tank.

I meant to say plants will get more oxygen into the water column than with an air stone.
Also read some of the stickies on ferts as well b/c you will need them to maintain heathly plants.

[lbritish]

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..

H2O + CO2 = H2CO3 an unstable chemical bond called Carbolic (or maybe Carbonic... do not remember the proper name for it) Acid. You may know this better as "Soda water". In the fish tank you add very little of this so it does not get fizzy like your soda but it is the same general principle. Obviously since it is an "acid" it goes lower on the pH scale the more you put in. By mixing CO2 with any water the pH will drop. The question is how much it will drop based upon chemical additives that lock the pH at a particular level. The only reason it will not go down is if you are inefficiently introducing the Co2 into the water column without using a device such as a difuser or a reactor or you are gassing off the Co2 with things like Spray bars, air pumps through air stones, or other agitation of the water that results in rapid gas exchange.



2# how do you increase the buffers without affecting the kh, buffers are carbonates or bi-carbonates which will dirrectly affect the kh

actually now that I look at what I wrote I totally screwed up what I was going for in that... TGenerally your fish like a particular GH which was not mentioned in the "test results". The KH with a few exceptions doesnt matter too much for many fish. What I meant to say was buffering the kH with well... hold on.... water chemistry google thing... here we go http://fins.actwin.com/mirror/begin-chem.html down around the altering water chemistry... Calcium Carbonate changes both... kH only is sodium bicarbonate...

Anyway my main point though is that most charts online are a little off when you get into the higher kH when you are trying to calculate the level of CO2 in the water and also that .1 pH can be a DRASTIC difference in CO2 concentration in some circumstances.

Regardless of accuracy of any of the other statements due to wording or scientific "weirdism" though there are 2 big issues with that tank. 1) Not enough light. 2) Inefficient dispersal of Co2 apparently into the tank.

To get a good idea of what is going on in the tank if we have the following in any circumstance anyone can give an educated set of guidance:

A) Dimensions of tank and volume
B) pH of water prior to the introduction of Co2 system
C) KH of water in the tank
D) desired GH for the tank
E) present GH for the tank
F) Light system on the tank.
G) Filtration on the tank
H) pH after you started CO2 on the tank

With those bits of information you can determine if the lighting is adequate or not and what the chemistry of the water will allow for CO2 and whether the CO2 is being mixed efficiently or not based on the observation of the plant reactions

Also regarding other statements about melting plants...

There are "susceptible" varieties of plants that will not be happy in hard water or in soft water... most plants dont like very acidic water... some grow better in neutral water instead of either end of the spectrum... If you need a particular pH then you need to make sure your plants match up or as I said they will "melt" or do other creepy things in many cases.

[RTR]

I believe that Tom Barr has identified a meager handfull of plants that do better in soft water; all the others, and all that are common in commerce, will do perfectly fine at any reasonable tap water KH/pH. Doing water mods for your plants is many times more likely to create problems than to assist in plant growth and health. Balance light, nutrients and CO2 and your plants will do well.

[ashdavid]

H2O + CO2 = H2CO3 an unstable chemical bond called Carbolic (or maybe Carbonic... do not remember the proper name for it) Acid. You may know this better as "Soda water". In the fish tank you add very little of this so it does not get fizzy like your soda but it is the same general principle. Obviously since it is an "acid" it goes lower on the pH scale the more you put in. By mixing CO2 with any water the pH will drop. The question is how much it will drop based upon chemical additives that lock the pH at a particular level.
The acid produced by this reaction "H2O + CO2 = H2CO3" is "carbonic acid", and what chemical additives did robson put in , none that I can see. What I don't understand is why you would say this,

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.
If you did not put in a buffer, the kh would not be affected and therefore the ph will go down due to the reaction that you stated before by carbonic acid being produced from the co2 input. So assuming a Co2 level good for growing plants is 20 to 25ppm and staying in line with what you said of keeping the ph at 8.2 the KH would then have to be increased regardless of the GH, this is b/c as you may already know there is a direct relationship with kh ,ph and co2. Another point I would like to clarify is that the level of Co2 in the water column is not affected if the kh is lowered or raised, it will affect the ph but not the co2 level, it will always be constant assuming that gas exghange is not a factor.
As for your last statement about controllers, I will say that unless there is something in the tank like crushed coral, ph controlers are fine to use. The problem with crushed coral is that as it dissolves into the water the kh rises which affects the ph, which is therefore counteracted by the automated controller b/c it has been set at a certain ph and will continue to try to keep it there, this then means the co2 level will rise in a vicious cycle. I assume that is what you were talking about.

[robson]

I turned off the air stone an the air injection into the filter output and after 1.5 days PH is down to 7.6-7.4

So it was the reason. Silly me :-)
I guess that now I have to check the PH and KH frequently to ensure that I wouldn't inject too much CO2 in the water and adjust bubble rate accordingly. Is that right?

I also wanted ask you one more question regarding the light. You measure the amount of light in wpg or wpl (watts per liter). But is that correct just for florescent bulbs, or for all bulbs. What I mean is that lat say energy saving bulb 20W should give same amount of light as ordinary bulb 100W. But in that case I don't know what wattage should I use as reference. I have feeling, that florescent tubes are sort of energy saving bulbs as well. So let say if I decide to buy powerful halide light. Is the formula still valid, I mean do I still need 300W halide light?

Thank you all of you for great help.

[robson]

Sorry,

one more question.

What brand and type of light would you recommned for my tropical tank?

[djlen]

Check your pH/kH relationship twice daily for about a week to be sure that you're getting the saturation that you want. I suggest checking at lights on and lights off.
You will note that at lights on your pH will be lower because the plants were not using the gas in the darkness. Some people turn the gas off at night for that reason. I personally do not, but leave it run 24/7 and show a very slight drop in pH....certainly not enough to warrant turning it off, IMO.
CF(compact fluorescent) is the lighting of choice for many aquarists. It is, again IMO, the most efficient for most tanks. The mid-range Kelvin rating (5500K - 6500K), to my eye is the most natural.
The wpg quotient applies for most lighting applications. Pay no attention to the 'energy saving/ordinary light bulb' sale pitch stuff. If it says 20 watts, use that as your yardstick.

Len

[ashdavid]

I have to agree djlen on the watt question, and I use MH lights with 5500k bulbs, my tank is about 400g which is about 1600L and use 4*400w lamps which gives me about 1w per L. I have used CF lamps and and the only benifit that I could see was that light was spreed out evenly over the tank, but that being said if you buy lots of lower wattage MH lamps you can get a pretty good light spreed. As for deep tanks MH lamps are the light choice, but in your case your tank will not be deep enough to worry about, I would say you could go with either MH or CF Imo.
I also think djlen has given you all should know on testing your ph and kh. goodluck

[lbritish]

WPG / WPL is actually not a good measurement because it has no bearing on the spectrum of the light. If you stick for example a blue light on the tank at 300 watts and then put a regular spectrum "daylight" style bulb at 300 watts then the daylight one will yield better results in the tank. This is an extreme example but the point being the color of the light that makes up your final output of the bulb due to the coatings of the bulb and/or the gas inside the tubes and the electric charge etc all impact the quality of growth you can get from one bulb over another. True "scientists" have very expensive meters that measure what is called Photo Active Radiation (PAR) or something like that. This is a measure of what registers with the plant for photosynthesis. Some spectrums are not good for plants while others are better. Best growth is with a variety. The Kelvin is a measure of the overal output of the spectrum of the light where normal incadescent bulbs are in the lower end of 3000-5000. Most aquarium lights are in the 6500 range. Many swear by 9600 for a whiter appearance. 10,000 + begins blueish

So actually the answer to your question really is no that just any bulb at a particular wattage the formula may not be accurate. When you deal with fluroescent technology bulbs the light formula works best. Things like MH bulbs will work similarly but due to some differences I feel that a MH bulb at 175 watts COULD in some circumstances work just as good as a CF bulb at 250 watts or even more depending on the height of the tank etc. The MH yields more ultra violet as well "raw" and is many times may have a UV filtering glass plate in many setups. The MH on the otherhand is a "point" light source instead of a spread source like the CF tube. As a result the MH will penetrate into narrow deep tanks very strongly. A CF tube has the light spread over a wide area.

So thus if you have a 6 foot wide tank that is 20 inches tall 2-4 CF tubes will work better then 1 175 watt MH bulb.

[robson]

Hi everybody,

I kept running the system with CO2 injection for about 3 weeks, but I still can't get PH to level 7-7.2. If the charts are OK, that I still haven't enough CO2 in my tank. I increased bubble rate from 30 to 50, but I still didn’t get a desired PH and CO2 concentration.
Does anybody have an idea what else could be wrong? Or should I just increase even more bubble rate? I was afraid to do it without I consulting it with you.
Thank you for any comment, thought or suggestion.

[Kissofthegorami]

I agree with you that lighting is your main issue right now. Lighting is the number one most important factor for growing healthy plants. You don't even need co2 below 2.5, 3 watts per gallon.

[robson]

I agree with you, but currently I'm in the process of moving from Ireland to Canada. I don't see any point to spent huge money on lighting, when it will not work in Canada.
On the other hand, it still doesn't explain why PH doesn't go down to level 7-7.2, or does it?

[RTR]

The crude "rules of thumb" on W/gal. assume the use of triphospher broad-spectrum tubes. If you go for alternate spectra, the "rules" no longer apply.

Reflectors control both light spread and penetration.

To dissolve CO2 effectively, use a reactor. They are easily and simply DIY'd. To retain CO2 in the tank, control surface breaks/agitation/aeration - but keep some current going below the water sirface.

[robson]

Isn't that glass thing on the page 1 of this thread reactor? Excuse me this silly question, but I'm really confused. If it's not, could somebody point me to the website telling how to make one DIY?

If it is reactor what could be the problem? There is no flow on the surface. I even tried to turn off filter for one day, but still no improvement. I'm getting desperate.

I understand, that everybody is trying to point me out to the fact, that I don't have enough light and therefore my plants wouldn't grove, as I want. My point is, that it seems to be simple for me to add some light at later stage, but I'm afraid that there will be enough light, but there will not be enough CO2 in the water and plants will not grow properly again. I'm trying to sort out the problem with CO2 first, because it's not affected anyhow by my relocation to Canada, and then I will just add proper lighting and everything should be all right.

[djlen]

I believe you have a tank of approx. 80 gals.
The reactor you're using is probably not going to be effective in a tank of that capacity. It's what is known as a passive reactor. You need either another one like it or an active reactor.
Please forgive me if this has been asked and answered before, but what kind of filtration are you using? This info. would help to decide if you can, in some way add on to your present way of injecting to increase absorption via filtration or if you'll need to pursue other options. There are many inexpensive DIY options.
I think you reported a kH of 130(7.3) and with a pH of 7.0 you would be holding 22ppm/CO2 which is a nice measurement for the lighting you are currently supplying. You really don't need much more concentration than that at your wattage. You will when you increase the lighting, but not presently.

Len

[robson]

My tank is 80 galons.

I'm using internal filter supplied with this Juwel 300L tank and as a filtration media it's using sponges.

At the moment I have KH 130ppm and PH at the moment is about 7.6 which is giving me something like 8ppm/CO2

[djlen]

I am not familiar with the filter you are using. Does it have an intake tube on the bottom? If so, you can direct the CO2 tubing into the bottom(or intake) of the filter and it can be actively dispersed into the water table by the filter.
If you can do this, I think you will find an immediate increase in CO2/ppm and in fact if you can do this with the filter, pay close attention to your pH so as not to over inject the tank.
I use an AC 402 power head to disperse gas into one of my tanks, similar to the method I'm suggesting you try with your filter, and this method is very effective.

Len

[beviking]

I guess I should have been more specific initially. Go to the Freshwater DIY section (drop down/up list at bottom right of screen) or try here at Plants forum and search for DIY Reactor and/or CO2 reactor for more ideas.
For starters, here is mine...
http://community.webshots.com/photo/66733948/209978429RguQNZ

Small pump pushing water down through a Flourish bottle. Water flows down, CO2 is bubbled in at the bottom. A few bio-balls/sponge help break up the bubbles.
HTH