CO2 and crushed coral

[toddnbecka]

I recently set up a 30 long, and mixed crushed coral with gravel for the substrate. Filtration is 2 air-driven double sponge filters. With 130 watts of light, what would be the best setup for CO2? Also, how will crushed coral affect the water chemistry as far as pH, gH, and KH with CO2 added?
The tank is primarily intended for breeding shrimp and dwarf crayfish, but I would also like to have good plant growth to make a better environment.
I have a similar setup in a 10 w/out CO2 and less light, about 2-2.5 watts/gallon. What plants would be suitable for this arrangement?

[Hypancistrus]

The CO2 will slowly dissolved the crushed coral, releasing calcium carbonate into the water column. (This is how a calcium reactor in a marine setup works.) This will cause the GH and KH (and therefore pH) to always be increasing.

[evercl92]

Originally Posted by toddnbecka

What plants would be suitable for this arrangement?

My guess would be none, unless dwarf crayfish are different than regular crayfish. They crayfish I had always tore the mininmal plants I had with it to shreads. Otherwise, with that much lighting, and CO2 addition, you should be able to grow about anything you wanted.

As the CO2 acidifies the tank water, the water will start to dissolve the CC. This will release Ca++ and CO3-- into the water, raising GH, KH, and eventually pH.

Best setup for CO2... do you mean DIY vs pressurized?

[daFrimpster]

most of dwarf crays are pretty much plant safe.

[toddnbecka]

The dwarf crayfish don't eat or tear up plants. I've read some threads and articles about CO2, but don't have any actual experience using it. My goal is to maintain a slightly alkaline pH, but I'm not understanding the necessary details of how to achieve that in the long run. CO2 makes the water acidic, which in turn dissolves the coral, raising pH and hardness. If the pH is 7.6 to begin with, and the KH is 5-6, how do I set up a CO2 system to benefit plant growth without lowering the pH too much? I want to have the tank established and stabilized before moving the shrimp/crayfish in.

[jaidexl]

crushed coral will leach what it wants, when it wants. i prefer adjusting change water with something like baking soda or seachem alkeline buffer, that way i'm always on top of the KH level.

[toddnbecka]

How much baking soda, and how often? If the KH is high enough, the coral won't be affected by the CO2?

[jaidexl]

i'm only trying to mantain 3dKH, so every week or so i add just enough seachem alkeline buffer to bring my 0dKH change water up to 3 or 4, which is roughly three pinches (the small scoop included with the bottle of buffer) to five gallons of water. they recommend adding one scoop to every one gallon of change water until desired KH is acheived. by adding three or four scoops thereafter to my change water, the tank's KH eventually drops to 2, so i just dissolve a few scoops in some water and toss it in the tank to get it back up to 3. it involves a lot of testing, but that's something i enjoy doing and i like to know where the level is at all times. i've had some nightmarish fluctuations in the past, so coral was never at the top of my list.

it's been awhile since i used baking soda, but if i recall, i was adding about one teaspoon to every five gallons of change water, give or take (i was still experimenting at the time). you'll want to play mad scientist in a bucket first to see how you need to treat your own source water. i decided to go strait to the tank at one point and messed up, completely destroyed my huge mass of pennywort.

[jaidexl]

Originally Posted by toddnbecka

If the KH is high enough, the coral won't be affected by the CO2?

the Co2 will cause the coral to buffer even more, increasing KH and making it hard for some plants to stay healthy.

[Rex Grigg]

1 teaspoon of baking soda will raise the kH of 13 gallons of water by 4 degrees.

[honor]

damn, i made the mistake of making a sublayer of crushed coral in my substrate. i guess i can always make water changes with distilled water.

[Carissa]

The CO2 itself will cause the water to become more acidic, but this type of change is usually thought to be harmless to the fish since it doesn't affect TDS and fish seem unaffected by it. The "true" pH of your water, so to speak, when you are running about 25ppm of co2, will be 1.0 higher than your reading. Nothing you do will change how much your pH drops with co2 injection (for dropping that is due to co2 injection directly, not due to leaching KH for instance), nor should you worry about it, it's a different type of drop and doesn't affect the fish.

Leaching calcium carbonate from coral, shells, etc. will be causing your water to become more alkaline by increasing KH (GH will also increase too, this does not affect pH), at the same time nitric acid from fish waste or other acidic compounds (such as tannic acid from driftwood for instance) will be trying to lower your pH. The best way to keep everything healthy is simply to do regular water changes which will keep the water in your tank very similar to your tap water (other than the drop in pH due to co2 injection, which as was already mentioned, doesn't matter). In a tank with few or no water changes, conditions eventually become unhealthy because there are always things building up, but nothing being taken out. 25% weekly is a good schedule for keeping everything stable and happy.

[MarkMc]

I think that most have already said: CO2 and your substrate (in it's present makeup) will result in higher ph values. If your tap water is 7.6 why would you want it higher? Marine aquarist use the same premise only it's contained in a reactor chamber and controlled by a ph controller-you'll have no such control with your set up. My advice:take out the substrate and replace it with something more suitable.