CO2 Injection Causes Phosphates to Rise?

[sleepylof]

I'm using CO2 Liquid Nutrient Plant Supplement 3pk (O.S.I.) from thatpetplace that has made the pH drop to 7.0 and raise CO2 levels to 20ppm, for about a week now. This has done wonders for my BBA problem... now it's much less prevalent.

However, I noticed that my phosphates were well over 5ppm. I did the 20% water change and haven't added phosphate directly to the tank nor is the water dirty. Does anyone know if liquid CO2 causes phosphate spikes? Thanks.

 

[PsiPro]

CO2 its self dosn't I belive. I was proably in what yo uadded since "liquid" CO2 is not pure CO2, they usually contain traces to help stimulate plant growth.

 

[sleepylof]

Thanks for the reply. I'm sure it'l be helpful to all of us who use this CO2 supplement. I guess it's important to do a water change prior to using the supplement and easing back on the phosphate containing fertilizer.

Thanks!

 

[malkore]

there's no such thing as a liquid CO2 supplement. Liquid CO2 is several hundred degrees below 0, so at room temp you cannot have liquid CO2..it instantly sublimates to gas (ever see dry ice 'melt'? no, because it sublimates directly to gas

I'm having a heck of a time finding any info on the net about the OSI Liquid Nutrient Plant Supplement. Could you possiblly list off the ingredients from the package?

A liquid CO2 supp (likely a carbon supp based off the chemical gluteraldehyde) shouldn't affect pH like true CO2 injection would. I suspect it contains a phosphate buffer, which explains the pH change and increased phosphates. The ingredients should confirm this.

 

[sleepylof]

Unfortunately, I've looked at the package and it doesn't list the ingredients... The net barely mentions anything about it too. Exactly right about the idea of CO2 subliming... back to chem.

This CO2 supplement has done a good job of raising my CO2 up to 20ppm, but it has also caused phosphates to rise to 5ppm (very high). It's great my CO2 is up to 20ppm (as it's been a struggle even with 2 Hagen DIY systems+CO2 supplement). I think what your're saying about the phosphate in the "liquid CO2" acting like a buffer to keep the pH at 7.0 makes sense.

Should I continue to use it? I'm afraid if I use phosphate reducers the pH will jump right back up to 7.4, and my CO2 levels that were keeping the BBA in check will drop again. ...Thx

 

[malkore]

I wouldn't use it. Your pH right now is skewed down by the phosphate buffer, which is why you think you have 20ppm of CO2...but you don't. Excel doesn't alter pH, because its not a phosphate, and it's not CO2.

Just to make sure you understand why CO2 lowers pH...CO2 creates carbonic acid in the water, dropping the pH. Because pH and Kh are tied together, a lowered pH via CO2 injection is compared to Kh and what the pH 'should' be at that level. Because pH is 'x' lower than it should be, we determine 'y' CO2 level.

You could pour hydrochloric acid in a tank and lower the pH too...but that doesn't mean any CO2 is added.

Its very possible your plant fert contains phosphoric acid (just like pH Down), and that's why pH is low and phosphates are high.

No need for phosphate reducers...just water changes and stop using this OSI plant stuff. They make good food, but apparently not good plant ferts.

I've made a Hagen 'ladder' diffuser work with pressurized CO2, on a 75 gallon tank, and hit 35ppm. Its a great diffuser design. If you didn't hit good CO2 levels, use a half gallon/gallon juice bottle for your CO2 generator, not the little grey canister that comes with the ladder (which is only suited for a 10gallon at most).
back that up with some Excel dosing if you like.

 

[sleepylof]

No more OSI "Liquid CO2." Too bad it doesn't mention on the package that it's use causes phosphates to spiral out of control.

I guess I could still use my Hagen ladder, but just drill a hole thru that juice bottle cap and seal the hole with silicone sealant? I'm a little new to making your own mixture for the DIY generator. Could you suggest what ratios of sugar, baking soda, and yeast to use for this 26 gallon tank? (I've been reading alot in other posts, but they vary considerably). Are there any other extras that I should be aware of when I use my own generator... ie, I guess check pH levels more often to make sure there isn't too much CO2 being produced? Thanks for the help.

 

[TankGirl]

Here is a link for some excellent reading on the subject: http://www.qsl.net/w2wdx/aquaria/diyco2.html#3

When I made my own generator I used a 11/64" drill bit for the bottle cap, which was just a frog hair smaller than the diameter of the tubing, and I cut the end of the tube at an angle to create a point, put the point through the hole and using needle nose pliers I pulled it all the way through, tight as can be, without any sealant necessary.

I used a cup of sugar and a rounded 1/8th teaspoon of dry yeast. I did not use baking soda. You will get a lot of variation with recipes but you can play with it and see what works best for you. Less yeast is better because more yeast will burn through the sugar quickly and you will have to replace the batch often.

HTH

Also, FWIW, for that size tank you could just dose with Excel every day and see if this solves your algae problem.

 

[malkore]

Silicone sealer doesn't stick to plastic very well. Best to just drill the hole slightly smaller than the outer diameter of your hose. I like to use the smallest size of rigid tubing, so I have a harder piece running in, and can easily connect a piece of airline to it.

If you have a leak around it, use something like that yellow sticky tack for hanging posters...it makes a great non-permanent seal as long as the plastic is dry and stays dry.


I never bothered with baking soda in my DIY mixes either. You may prefer 2 small DIY generators connected with a T, then going into the tank...and start them about a week apart from one another, so you only have to change one mixture out at a time.

 

[Purrbox]

Personally, I love using the Fourmost Bulkhead Fittings that are suggested in the article that TankGirl provided the link for. They make a great machanical seal with very little fuss. The one thing to watch out for is that I had to use the Large Fittings (blue and yellow) instead of the ones pictured (green and red) to get a good fit with my tubing since the regular ones were just plain too small. They run about $4.50 for a pair.