Low light, CO2, problems - time for a change?

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zenkatydid

Aquarium Advice FINatic
Joined
Jul 30, 2005
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This will be long, I apologise. I'm starting to get frustrated and need to do something.

We are running two tanks here - a 50gal and a 28gal. Both are about 1.5wpg, both have DIY CO2, are medium-planted and lightly stocked. Both have developed mild staghorn and BBA, with the 28gal being a little worse. This tank also has a waterfall filter so it's harder to get CO2 up.

Why am I adding CO2 on low light tanks? Well, I was hoping to add some medium light plants, and get away with it. And I do seem to be able to support some medium-light plants, so maybe it's working, I don't know. Maybe it's coincidence!

I guess what I'm asking is - should we abandon the DIY CO2, stop doing water changes and go with the low-light Barr method? My concerns:

1. I have had plants in both tanks (swords) show signs of K deficiency, so have been dosing K. NO3 and PO3 are also very low, and I plan on dosing those (as soon as my ferts arrive). Is dosing ok in a no-water-change tank? I will obviously not be doing EI, but a test-and-dose scenario to get it at the right level.

2. In my 50gal, I have 2 bristlenoses. They are filthy. Piles of poo gathers underneath the driftwood where the biggest lives and it's vital that I do a gravel vac. Can I still do a weekly gravel vac and water-replace? I need to remove 10-15% to do a decent vac.

And finally - has anyone ever got DIY CO2 to be stable? Anyone running it who does not have a BBA/staghorn problem? At the moment it just seems to be creating more problems than it's solving :/
 
You can help take some of the fluctuation out of DIY CO2 by running multiple bottles and alternating when you change the mix. This just helps and will not completely eliminate the fluctuations. The key is to maintain CO2 levels above 30ppm at all times. If your CO2 is below this at any time while injecting CO2 you are bound to end up with BBA sooner or later. You may need to add additional bottles for CO2 generation or switch to a more efficient diffusion method if you are having troubles achieving these levels. With the tank that has the waterfall, you may be better off abandoning CO2 as it is going to be difficult to get descent CO2 levels unless you replace the filter.

You can gravel vac a planted tank in any areas where there aren't plants. Absolutely no problem with removing the driftwood to give the gravel under it a good vac and remove that fish waste.

You can dose in a limited/no water change tank, you just don't dose nearly as often as you would in one where you are doing frequent water changes. You're probably looking at once a week at most, unless you've got an extremely light bioload and heavily planted.
 
I do cycle the bottles - 2 get changed each week. Maybe I should have 8 bottles, changing 4 each week? What is a more efficient diffusion? We are using standard airstones at the moment, but I have seen glass pipe-shaped diffusers and stairway type diffusers - are they better? Is there a 'best' type?

With the waterfall tank, would adding Excel have any benefit, or would that offgas as well?

At the moment I am thinking I will remove the CO2 from the waterfall tank and work on it on the big tank. I would dearly love to have a stable high CO2 environment, but I just don't know if DIY is up to the task.
 
on my 75 gallon i alternate 6 2L bottles pair is changed every weekend...i diffuse my CO2 by running the air tube right into the intake of a powerhead. my Powerhead is located about 1/3 up from the bottom of the tank, and has an adjustable outflow that i have pointed slightly down. the powerhead spits out a mist of CO2 about every 2 seconds and i would say 95-98% of the CO2 never reaches the surface of the tank. i get between 55-60 ppm CO2 according to my reading... your results may vary :D
 
A general guideline is 2 Liters volume for CO2 generation for every 10 gallons of tank volume. Going by this you'd want about three 2 Liter bottles for the 28 gallon and five to six 2 Liter bottles for the 55 gallon.

Unless that airstone is sitting under a filter or powerhead intake, that's about the poorest diffusion method available. Basically there are two broad groups of diffusion, passive and powered. Passive diffusion involves prolonging CO2 contact with water to encourage diffusion, while powered diffusion actively breaks up the CO2 forcing it to diffuse. Powered diffusion is almost always more effective than passive diffusion.

I believe that the current 'best' method would be using CO2 mist, closely followed by using a powered reactor which can be either intank or inline.

What are you current KH and pH levels in each tank?

Excel is a liquid carbon source, not CO2, therefore it doesn't gas off. It would definately be a viable option for supplementing or replacing your DIY CO2 on the 28 gallon. Might be more cost effective to just replace the filter though as Excel will get rather expensive over time.
 
personally i really like the results i am getting using the powerhead, so much so i think even if i switch to pressurized someday i will probabaly still diffuse my CO2 in this manner
 
Ok, the through-powerhead thingy sounds like a good option. I will have a go at attaching the CO2 tube in-line, and if I'm still not getting the results, I will add some more bottles.

JDogg, you say you use 6 2l bottles with 2 changes every week - I am changing 2 every week, I think the bottles only last about a week and a half before they trail off. How is having 6 any different to have 4, if you only change 2 a week? Or do yours last longer?
 
What kind of mix are you using?

The mix I used for a while, which lasted around 3 weeks before fading out is as follows:

1/8 tsp champagne yeast
2 tsp of powdered milk (or protein drink mix)
1C sugar
1T molasses
1 tsp baking soda

Apparently you can leave the yeast in the bottom from the previous mix and put in all of that stuff (with water) you can reuse it all. It stunk so bad by the time I emptied them that I usually just cleaned the bottles and started fresh each time.

I got that recipe off of http://www.aquatic-gardeners.org It worked very well for me.
Here's a link to the powerpoint "article"
 
i am using 2c sugar, 1/4tsp yeast and a pinch of baking soda. sounds like i need to change that!

what is the purpose of the powdered milk and molasses?
 
Just to agree with Purrbox and JDogg, DIY CO2 on a large tank won't get real good results, but these results would get better with CO2 mist. My way of doing it is 1 powerhead for the mist, have an airstone directly under the powerhead with the CO2 going to the airstone. Preferably a limewood airstone, as it will give off a very fine mist. Then 2 more powerheads at the surface of the tank, on the back wall, pointed straight forward and slightly up. This will give more surface aggitation, increase O2 levels, as well as kick the rising CO2 bubbles back down the front glass and back under the plants. This will maximize the amount of time the CO2 bubbles are in the water in the plants. Without the upper powerheads, the CO2 will just rise and escape the top of the tank. Also, with the powerheads facing slightly up, they will not disturb the plants as well, so you won't have plants going every which way. I like Rio 180's for the 2 upper powerheads, as they are small, and are not very visible when at the surface of the water, and don't have a lot of power to create too much disturbance for the plants, but yet they are powerful enough to do the job you want. I have 1 on my 29G, and 2 on my 75G.
 
zenkatydid said:
i am using 2c sugar, 1/4tsp yeast and a pinch of baking soda. sounds like i need to change that!

what is the purpose of the powdered milk and molasses?

If you read the power point that I linked it explains it pretty well. Basically the yeast needs amino acids to thrive. The molasses and powdered milk (or protien drink mix) provides that. If you don't include that stuff in your mix, your yeast will basically starve to death before using up all of the sugar.
 
i don't have ppt, so can't view the thingy :/ i will do a google search and see if i can find it in another form. thanks for the info, everyone! i will try the new yeast mix and the inline thingy this weekend. i'm sure it'll help heaps.
 
That viewer is basically just a plug-in for Internet Explorer. It will allow you to view Power Point Presentations in your browser. Nice to have.
 
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