Aeration in planted tank

I think basically what Tom's saying is that with the light intensity you're talking about, the plants will use all the CO2 available causing the pH to rise. At a lower light level injection might not be needed.

Yes, each tank has a different level of balance and therefore different requirements for CO2, nutrients etc.
The rule of thumb for 'high lighted' tanks is actually more like 25 - 30ppm CO2. Since you don't have your tank up and running you can take a sample of tap water. Let it gas off over night or at least a few hours. Then do a KH and a GH test on it to determine how hard(GH) your water is and also the degree of 'buffering'(KH) it has. Then, once you have the tank filled and running you test your pH and compare that value with KH to determine CO2/ppm. Generally, tap water(that is left to gas off) and tank water carry approx. 2 - 4ppm CO2.
Len
 
Yes, the first part is correct(not enough Carbon from the gravel at 4w/gal etc) and the range I tend to shoot for is about 20-30ppm CO2.

The pH will go up simply due to removal of the acid by the plants, the acid is the CO2 in the water. There are other potential processes that can raise the pH as well.

HCO3 is "the KH" at the pH's we used.

CO2:HCO3 ratio determines the pH _generally/ideally_ in most plant tanks.
CO2=>the acid and the HCO3 the buffer. A balance of the two gives the pH.
Remove the the acid, the pH goes up, remove the buffer/base the pH will go down.

Now I see no reason to add anything other than CO2 to lower the pH for the plants. If you use something other than CO2 to lower the pH, then the pH range has little meaning regarding plants. Plants want CO2 , not some "acid buffer" to grow. Plants need a lot of carbon to grow, if it's not CO2, don't bother. Excel can work also but only at lower lighting and the CO2 will work better IMO/IME.

You can depress the pH with other chemicals(other than (CO2/HCO3), but then the pH/KH/CO2 relationship is altered. It also complicates something folks are already having a tough time with and makes it VERY difficult to measure the CO2 and see if the plants are getting enough enough CO2.

This measurement is important espeically with high light system.
Even if you don't understand acid/base chem don't worry, this is the why, the how is easy. Use CO2 gas for this light intensity.

You can still use this product though................it's certainly would not hurt:)
But I'd use CO2 gas for sure in your case.

Regards,
Tom Barr
 
Tom,

I have already decided, based on your and other previous posts, that I will add the CO2 system.

Do you think that I am going overboard on the lighting? In a different post, i was recommend to get more light than I had (I have a ~70w set that I am going to return). This is why I ordered the 2 x 96 w which will give me ~4 wpg.

Thanks for all your advice. I actually understand acid/base theory rather well. I studied chemistry for quite a few years. I was just a little confused with the way you worded your post. But, I have it straight now.

I am sure as I get this tank set up (I hope to put water in it within the next two weeks) I will have even more questions.

Thanks again

Dave
 
I'm not a serious planter, but I've heard that 3 wpg is plenty. Of course, I'm not gonna try to upstage anyone else here, I'm just trying to get you a response sooner...however, if you have already ordered the other lights, you might as well go with them.
 
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