our first planted tank, and some questions

[chris_todd]

So our first planted tank (a 20g high) has been going for a few weeks, with water sprite, java fern, val, and a "compact sword", as well as three fairly young giant danios, all purchased from Scales. They are planted in Fluorite, and I stuck Seachem Flourish tabs about every 4 to 6". No CO2, and two brand new 15W fluorescent bulbs - an aqua glo 18000K and flora glo 2,800K, on about a 12h schedule.

The plants seem to be doing well, or at least they're not shriveling up, turning brown and dying. The water sprite seems to be thriving nicely and is throwing off very fine hair-like structures from the tips of a few branches. You'll get pictures after the October meeting when I learn how to photograph my tank.

I was testing the water last night and noticed a few things that didn't immediately make sense, and wanted some feedback on my conclusions. My tap water is pH 7.8, 8 degrees GH, 4 degrees KH, with 10 ppm Nitrate. Initially, this was basically what the tank read as well, but now the tank is reading pH 7.4, nitrate about 7, KH between 2 and 3, and GH of 12. Zero ammonia and nitrite.

So I was wondering how it was that the pH went down, the KH went down, and the GH went up so much? Did the flourite and flourish tabs increase the GH? What might make the pH and KH go down?

And for future tanks, is flourite really "all that"? Can I just use plain brown 2-3mm gravel with flourish tabs and get the same results, or is there really something special about fluorite? I seem to recall flourite was considerably more expensive than plain gravel.

Chris Todd

[SCMurphy]

There is nothing shocking about the change in water chemistry you saw. DOn't worry about it. Flourite is a substrate that is not inert, it has a CEC capacity and will attract and hold onto nutrients until your plants send roots down and use them. It is better than plain gravel.

[ddavila06]

you can used african root wood or some other tipe to help and lower your ph if it is a concern to you. and add a little rustic touch too

[ingg]

Damian - Using wood doesn't change the base effect of what is making PH in a water column - neither does CO2. They are false positive so to speak - what you worry about is GH and KH, not PH in that sense. Loading a tank with driftwood to change PH doesn't change the base qualities of the water, and shouldn't really be used as an attempt for such.

Chris -

You should expect GH to climb, because of the substrate that Sean mentioned. CEC is Cation Exchange Capacity. It essentially tells you that the substrate will suck minerals and nutrients from the water column, hold, and slowly release them. This is a good thing in a planted tank, it lets the substrate become a time release of the goodies plants want.

You should expect KH to get lower, as vals in particular suck cabonates from the water column to grow with, this will lower KH.

Since you are lowering KH, PH will change, they are related.

In short - your reading are a good thing!

[ddavila06]

oh weill, i don't know what or how it happens but the ph is lowered since i added those woods...

[dSerk]

you can used african root wood or some other tipe to help and lower your ph if it is a concern to you. and add a little rustic touch too

Someone at the petstore (SuperPets in Annandale on 236) told me African Vine Root raises pH, makes it more alkaline. He said it was good for African Cichlid tanks. I guess it's a moot point if wood does not affect pH, but doesn't it affect hardness at all (and thus pH...)?

[Cristy Keister]

Someone at the petstore (SuperPets in Annandale on 236) told me African Vine Root raises pH, makes it more alkaline. He said it was good for African Cichlid tanks. I guess it's a moot point if wood does not affect pH, but doesn't it affect hardness at all (and thus pH...)?

I think that someone was confused. Wood can lower pH, not raise it. Ok, maybe if it's driftwood that has been soaking for a very long time in the ocean and has lost it's own acids - but you don't find that in fish stores.

[krisw]

I'd agree with Cristy's assessment. They probably thought that "African" wood was good for "African" cichlids. My experience has often been that a fresh piece of wood may have an effect on pH, but over time, that effect becomes more and more negligible.

[RTRJR]

Second Cristy and krisw's comments and thoughts. Fresh wood (meaning not presoaked, not green) will lower pH & reduce KH (same thing), but it an operating tank with routine water partials the effect is trivial and declines markedly over time. If you pre-soak the wood until it sinks quickly, the tank effect will be all but unmeasurable other than in massive pieces.