Why won't my CO2 levels go up?! Please HELP!

[cgcaver]

Hey guys, I'm really hoping some of you can help me out here. Here's what Im working with:

-55g
-3.75wpg bright kits
-AC500 filter
-No fish currently in tank
-Plants: 4 Amazon swords, some java moss, corkscrew val, anacharis, some -new glosso clumps
-Substrate: large rock and flourite
-Pressurized CO2 w/ CO2 "proof" tubing (the expensive stuff)
-Homemade diffusor (rio200 pushing water through a gravel vac tube with bubbles in it - i.e. http://www.aquariacentral.com/forums/showthread.php?t=50905 )
-Tap water is about pH 7.8

First I tried having the CO2 diffused by my AC500 impeller (I just stuck the hose in the intake). I knew this wasn't optimal, but CO2 is cheap and I figured it was worth a shot a first. That didn't produce much at all in the way of CO2 ppm, so I decided to go ahead and build the diffusor I have now. I cannot seem to get my C02 levels above like 3-5ppm. Here are some numbers for you:



June 12 - Tanked CO2 had been going into tank for about 24 hours, into the AC500 intake to be dissolved by the impeller. Very high bubbles per second (was trying to saturate the tank).

pH: 7.4 (as you can see, my water pH dropped .4 from the usual 7.8)
GH: 3 degrees
KH: 5 degrees (6ppm CO2)
PO4: 1.5
NO3: 20
NO2: 0
NH4: 2.0 (I have no freakin idea where this Ammo came from... my snails?!)



June 23 - I have had homemade diffusor up and running for about 24 hours now. Running between 1-2 bubbles per second. I had a big algae issue going on (prolly due to PO4 levels), with very hazy water - tried a 3.5 day full blackout, which didn't clear up the hazy water (usually does) - so I did a 90% water change today.

Before water change:

pH: 7.4 (pH was obviously holding steady)
GH: 4 degrees
KH: 3 degrees (3.5ppm CO2)
PO4: .5
NO3: 7
NO2: 0
NH4: 0 (Something obviously took care of my ammonia mystery)

After 90% water change:

pH: 7.9 (ouch - pH jump :\ )
GH: 3 degrees
KH: 5 degrees (1.8ppm CO2)
PO4: .5 (Im starting to think something is wrong with my Phosphate test kit - it never looks very colored like the match card)
NO3: 0



So... big pH jumps... not good. Very little CO2 in my water, after spending insane amounts of money on this ... very not good. And glosso not growing fast ... worst of all! OK, so thats a side note and Im impatient... but I seriously pray every night before bed that my glosso will not die and actually spread But anyways, I could really use input from yall, as it seems I will never achieve 20ppm CO2. I've spent a lot of money and I am gettin no results... this is so depressing. What should I do to increase my CO2 to that level?!

Also, 2 more quick questions, then I'll sit back and hope for replies:

1) I notice a fair number of small bubbles coming out of the bottom of my reactor tube that just float right up to the top... should i put some sponge in the bottom? Will this help diffuse more gas?

2) My tank has a ton of tiny bubbles all in it... seriously it looks like my tank is filled with Sprite. There are tons of bubbles coming from all of my plants, and even on the side of my tank. There are tons of bubbles especially after a big water change. Is this normal? What am I seeing... oxygen?

 

[hashbaz]

Wow... I really don't know what the problem is. It sounds like you are getting a lot of CO2 into the water. My guess is that you have a CO2/KH/PH relationship issue.

I know someone will ask if you let the tap water sit out overnight before measuring the PH. Do you know what the PH of the aquarium is after turning off the CO2 for a day or two?

The CO2/KH/PH relationship is only valid under certain restrictions. Carbonates, and CO2 must be the only things affecting PH. Ammonia and phosphates (among other things) can affect the PH and throw off the CO2/KH/PH relationship. I'm sure there are other restrictions, but I have not heard them.

If you simply turn off the CO2 and see a decent rise in PH (after some time) and then a drop in PH when you turn the CO2 back on - you will know that you are getting significant CO2 into the water even though the CO2 table says you have little #ppm. The CO2 charts or the CO2/KH/PH relationship would not be valid.

Your 2 bubbles questions:

1. If the number and size of the CO2 bubbles escaping the reactor are small compared to the bubbles going into the reactor, you have nothing to worry about. Otherwise, you should get a sponge.

2. During water changes (especially if there is a lot of "sloshing around") air bubbles will often collect in the aquarium. No big deal.

Is there a lot of splashing or surface agitation from your ac500? This would cause CO2 to leave your aquarium faster.

PS thank you for including so much information in your post! It's hard to trouble shoot without the facts.

 

[hashbaz]

My tank has a ton of tiny bubbles all in it... seriously it looks like my tank is filled with Sprite.

Sprite is saturated with CO2. It is not possible to saturate a tank with CO2 - Is it?!? I would guess that the return from the filter is making bubbles that are stuck everywhere. Does the return water from your filter have to drop before reaching the water surface of the aquarium?

I'm sorry my thoughts are so jumbled. In conclusion I have three guesses:

1. There is not enough CO2 because the filter is causing splashing, bubbles, surface agitation etc. causing CO2 to exit the aquarium.

2. There IS enough CO2, but there is something in your water invalidating the CO2/KH/PH relationship.

3. There IS enough CO2, but your test kits might not be terribly accurate.

Keep us posted.

 

[greenmaji]

First off if the water level isnt high enough to submerge the output of the filter I would suggest that you do that..

Question 1 yes put a sponge on the bottom of the reactor tube.. put some bio-balls in there while your at it..
Question 2 are the bubbles coming from the bottom of the plants or are they just stuck to the plants all over? have you seen a picture of pearling plants?

Do you diffuse the water going into the tank somehow from the water changes? are you using a bucket to fill your tank or a python? if your using a bucket I would suggest that you use a colander to lower the amount of splash caused by the dumping of it..this can cause O2 bubbles on the tank walls Ive had them on fish only tanks.. Im only saying this because you mentioned bubbles.. you shouldnt be getting any bubbles from CO2 in the tank.. they should be in the reactor only.. the AC input should have worked but it sounds like you have a gas escape issue or your just not waiting long enough for the acids to lower the PH.. the water changes will cause the ph to come up but not over the tap waters PH.. it sounds like your rocks might be leaching calcium carbonate though your tests dont seem to indicate it.. making your water harder and rasing your PH.. creating sort of a calcium reactor out of your tank... you might want to try removing the rocks to see if that helps.. ACK long post! LOL

 

[Steve Hampton]

Let's start with basics first. We MUST discover the baseline pH your tank is starting with prior to CO2 injection. As hashbaz alluded to in the first post, it is very important to do the following:

1) Remove a cup or two of your tank water and place into an open bowl.

2) Place an airstone in the bowl of water and aerate for at least on hour, let is rest for twenty minutes then take a pH and KH reading on the water. The point of this exercise to outgas CO2 until it reaches equilibrium or about 2-3 ppm of CO2.

3) If you don't have an airstone and air pump, then leave the bowl of tank water undisturbed for 24 hours to allow all the excess CO2 time to outgas and reach equilibrium.

Using the pH and KH information gathered from this simple little test will allow us to determine how much CO2 is being injected even if you have KH test kit interference from another acid or base.

It's my guess you were getting a fair amount of CO2 dissolved into your tank as evidenced by what sounds like pearling. Hold off on increasing the CO2 unless we do this quick test. After establishing the baseline, setting the CO2 levels, then you'll need to address the additional nutrient demands of your faster growing plants...but one step at a time.

 

[malkore]

Also, I'd take a sample of water and rush to the LFS and have them test your pH. Perhaps your kit is totally off.

Do you have lots of bubbles stuck to the glass tank walls? or are they only on the plants, and they quickly float up to the surface? bubbles on tank walls would be gases from the water change being released...bubbles only on the plants would indicate pearling.

YOu're not using ANY sort of pH buffer correct?

 

[cgcaver]

thx so much for all the input guys - i studied each word


No I dont have any pH buffers and I tested all my rocks with vinegar before buying them (arkansas river rock). I will do the test with the bowl of tank water and let you guys know my equilibrium numbers. thx!

 

[cgcaver]

I have no airstone in my reactor. I keep my tank slam full of water so my AC500 doesnt make much surface agitation. I turned down my light from 3.75wpg to 1.75wpg so my plants wouldnt "eat themselves." I do not use any type of water buffers at all. My substate is flourite with Arkansas river rock (I tested it with vinegar before I put them in my tank - no bubbles when vinegar was poured on them). I even increased my bubbles per second drastically, and all that seemed to do was create a big air pocket a the top of my reactor. I think this answers all the questions ppl had.

Readings from my tank still indicate that Im only hitting about 6ppm CO2. This is so depressing... To make matters worse, I now have terrible "green water" algae, so Im doing a 48 hour black out (all I can think of is I over dosed some nutrients after i did the big water change). Im starting to lose all hope


OK, here's an update:

6/26/05 Sunday

pH - 7.4
NH4 - 0
NO2 - 0
NO3 - 0
PO4 - .25
GH - 3
KH - 5



Someone from one of the forums asked for this info, so let me post it:

My Tap Water:

pH - 8.2 (yeh its like a rift lake coming outta my sink )
NH4 - 0
NO2 - 0
NO3 - 0
PO4 - .5
GH - 2
KH - 5



I put 4 cups of water from my tank into a bowl and let it sit, so I could get a stable equilibrium reading from my tank water. Here's what I got:


After 24 hours of sitting:

pH - 7.6
GH - 2
KH - 6

After 72 hours of sitting:

pH - 7.8
GH - 2
KH - 6

There you go Steve, theres the numbers. Im not sure what this tells you, but Im praying you have answers for me Hope this helps. If anyone can please tell me what is going on, and why my CO2 levels in my tank wont go up, I would greatly appreciate it.

 

[Steve Hampton]

Great follow up information.

With this information we can determine that your KH test kit is fairly accurate and is not being influenced by anything in your tank. This leaves one of two possible scenarios, having just eliminated several others with your testing.

1) Your pH test kit is unable to give you a good reading below 7.4. If this is the case you could pump in tons of CO2 without being able to tell. Some pH kits only have a range to 7.4...consider using an electronic pH meter/monitor or at least buying a good low range pH test kit.

2) Your reactor is doing a poor good job.

I'd bet more money on number 1 being right. You noted pearling earlier in spite of not having the pH reflect that CO2 was being dissolved. Plus, with your KH any sort of a reactor being feed 1-2 bubbles per second should still produce good CO2 saturation. It really seems to me as though you had good CO2 levels, but your pH test kit wasn't showing less than 7.4 You could test the pH of distilled water. It should read 7.0 or slightly below. If your test kit determines the right pH for distilled water then we'll need to dig a bit deeper.

 

[cgcaver]

OK Steve, i totally get what youre saying. I'll pick up a low range pH kit tomorrow. One question I have tho is... How in the heck am I supposed to keep African cichlids happy in water that acidic? They like pH of around 7.8-8.2

 

[Hoovercat]

You can add crushed coral to increase ph but you might not reach 7.8. From what i gather around here stable ph is a lot more important than having the range specified for your stock.

 

[Steve Hampton]

Have you seen Travis's tank? They (African Cichlids) actually like hard water, if the pH is acidic only from carbonic acid (from CO2 injection) it doesn't have any noticeable ill effects...they breed, eggs hatch, fry survive. Remember we are only changing the pH temporarily with CO2...stop the CO2 injection and the pH returns to it's equilbrium starting point. Where you have problems is when the pH is low due to softer water...which you actually do have an issue with...increasing your GH would be a good plan for keeping African Cichlids...your plants will like the additional calcium and magnesium too.

Here's Travis's tank.

Note his water pH and hardness.

Water parameters are: Temp 78F, pH 7.2 (low for Africans, but I've slowly acclimated them and they show no ill effects and are, if nothing else, breeding even more prolifically Smile), KH 14, GH 18

http://www.aquariumadvice.com/viewtopic.php?t=39189&highlight=planted+mbuna

 

[madasafish]

Hi Cgcaver,

Your case is a bit of a conundrum. I have a question and a couple of suggestions...

1) Are you sure that the pressurized tank you have is filled with CO2? It's a pretty silly question, but it's the only obvious question that hasn't been asked yet. Thought I'd give it a shot. If you were really bubbling CO2 furiously into the tank, even without a diffusor, the pH and CO2 levels should have changed *drastically*, and very quickly. IME, bubbling in CO2 at hundreds of bubbles a minute can drop the pH of a 55 gallon by 1 degree or more in a few minutes.

2) I'd strongly advise buying yourself a pH regulator if you do not already have one. Mine gives me indescribable peace of mind because I can always see that my pH is between 6.6 and 6.8, the optimal range given the KH of my water. The Milwaukee model is the obvious (and by far the cheapest) model.

3) I agree with the others that the KH softness of your water does make this more difficult. If you look at the graphs on this page: http://www.thekrib.com/Plants/CO2/kh-ph-co2-chart.html , the softer your water, the more difficult it is to increase its CO2. I use some Texas Holey Rock to naturally buffer up the KH of my water to 5 or 6 degrees, and my CO2 values are easy to achieve by just slightly changing the pH of the tank with CO2 injection. Others use crushed coral, as mentioned above.

Best of luck with this situation. I work for one of the top CO2 air-sea interaction scientists in the world, and I must admit that I'm otherwise stumped, unless some of your equipment is broken/malfunctioning.

Quizzically yours,
Jon

P.S. In the future, you'll want to wait on glosso until your tank is well established. It can be a difficult plant to keep, and relies on stable conditions.

 

[cgcaver]

Well I'll be a son of a monkey's uncle. Looks like the mystery has been solved! Steve, I owe you big time for your input on this one

I went and bought a Low-Range pH kit and it turns out my pH is actually around 6.8-7.0 LOL so... that means im getting 18-28ppm CO2. YES!!!

Now my only quandary is how I'm going to raise my pH. 6.8 sounds awful low for Mbuna... Would you guys recommend using crushed coral? Is that something I would have to add once, or periodically? Is there a better alternative? Also, would that increase the GH of my water? If not, what could I add to increase hardness, since Mbuna like hard water?

 

[greenmaji]

CC in the filter would work..

 

[Steve Hampton]

Well I'll be a son of a monkey's uncle.

Sounds like we may be related.

Looks like the mystery has been solved! Steve, I owe you big time for your input on this one

Your payment is to help someone else with a similar dilemma.

Now my only quandary is how I'm going to raise my pH. 6.8 sounds awful low for Mbuna... Would you guys recommend using crushed coral? Is that something I would have to add once, or periodically? Is there a better alternative? Also, would that increase the GH of my water? If not, what could I add to increase hardness, since Mbuna like hard water?

Here's more information than you probably wanted to know.

Using Crushed Coral:

This adds calcium carbonate. Calcium carbonate is largely insoluble...however carbonic acid (CO2) increases it's solubility. Adding calcium carbonate in the form of crushed coral is a bit unpredictable. It will raise GH due to the calcium, and KH due to the carbonate, and pH because KH and pH are directly linked. The amount of the increase and the time the increase takes is largely unpredictable. For this reason I'm not real fond of this method. You can purchase calcium carbonate in a powered form from Greg Watson online or a local wine/brewing supply store. Adding powered calcium carbonate is predictable and because you can measure it you know how much you'll raise your GH, KH, and pH with a "dose". The powered form of calcium carbonate will cloud your water for a few hours after adding until it's dissolved. (Note I didn't say fully dissolved)

The other issue of using calcium carbonate or CC is it only addresses part of the hard water constituents. Ideally, Magnesium should also be included at a 4 to 1 ratio of calcium to magnesium.

Commercial products such as Seachem Equilibrium address all these issues and is an excellent choice though it can get expensive. You can purchase calcium carbonate and Magnesium Sulfate and mix your own if your so inclined and safe a lot of money if you'll be using a lot.

Considering the success Travis is having I would copy his method.

Yoohoo, Travis...

 

[RoLeX]

Using Crushed Coral:

This adds calcium carbonate. Calcium carbonate is largely insoluble...however carbonic acid (CO2) increases it's solubility. Adding calcium carbonate in the form of crushed coral is a bit unpredictable. It will raise GH due to the calcium, and KH due to the carbonate, and pH because KH and pH are directly linked. The amount of the increase and the time the increase takes is largely unpredictable. For this reason I'm not real fond of this method.

Hi all,

dont use these forums a whole lot im on some others.

I dont want to be a smart alek but Crushed coral and things like limestone are a buffer which means no matter how much u have in the tank the ph will only go as high as the buffer allows eg. u can have a ton of limestone in a tank but it still wont exceed a ph of 8.5, ive had a 6 cm layer of crushed coral in a 80 litre tank and ph hits around 8.3 to 8.4 and never more or less. So im my opinion using CC or limestone would be fine in the tank and it is not unpredictable.

Any way as i said correct me if i am wrong, jsut tryng to sort things out

 

[greenmaji]

Hi all,

dont use these forums a whole lot im on some others.

I dont want to be a smart alek but Crushed coral and things like limestone are a buffer which means no matter how much u have in the tank the ph will only go as high as the buffer allows eg. u can have a ton of limestone in a tank but it still wont exceed a ph of 8.5, ive had a 6 cm layer of crushed coral in a 80 litre tank and ph hits around 8.3 to 8.4 and never more or less. So im my opinion using CC or limestone would be fine in the tank and it is not unpredictable.

Any way as i said correct me if i am wrong, jsut tryng to sort things out

its cool.. CC and limestone will only work untill a certain PH.. like 8.5 is reached then it stops disolving.. as you said.. CO2 continues to artificaly drop the PH forcing the CC and limestone to continue to disolve past this point untill the PH of 8.5 or so is reached with the CO2.. the actuall PH can become alarmingly high.. and this is how a calcium reactor works for a reef tank if you would like to look up some examples of how it works..
otherwise.. CC and limestone are pretty much harmless.. HTH

Ive leard a little since this post.. the guy really didnt need his PH up.. the low Ph was just indicating his CO2 was working...LOL how goofy I was..

 

[RoLeX]

its cool.. CC and limestone will only work untill a certain PH.. like 8.5 is reached then it stops disolving.. as you said.. CO2 continues to artificaly drop the PH forcing the CC and limestone to continue to disolve past this point untill the PH of 8.5 or so is reached with the CO2.. the actuall PH can become alarmingly high..

dont have time to read up right now quite busy atm, but was jsut wondering will the ph level only become extremely high if the co2 is stop being injected? and if so is this a continual build up since co2 is continually injected and then once the co2 stops can it jump to say 10 for eg.

or do the 2 just dissovle(or counter act wth each other) each other out until a stable ph is acheived. Thanks for ur help.

 

[malkore]

Rolex,

the effect on pH when adding buffering and injecting CO2 is widely debated. many of use are not scientists, just hobbyists.
some subscribe to the belief that even with little to no carbonate buffering, CO2 injection is fine because 'what little buffer is there will just work harder to prevent wild pH swings).'

others like myself don't buy into that...the more buffer you have, the more the water will resist a large pH swing.

I beileve there is evidence, though, that over time, carbonic acid eats the carbonate from the water...so assuming you did no water changes, the CO2 injection would simultaneously eat the carbonate hardness, and cause the rock/CC to break down and increase the hardness.
As far as an upper threshold, I think you're right. If we think logically, if we could measure pure carbonate hardness on a pH scale, it'd probably come out around 8.5pH...possibly a little higher in a special controlled environment.