soft water and CO2

[medge00]

Ok, so as I understand it, DIY CO2, or maybe the Hagen system, would be bad for tanks like mine as I have extremely soft water... I tried Seachem's Neutral Regulator but that had no effect (I have water with a PH of 7.8ish). I'm not too worried about the PH as it seems to stay fairly stable, I just would really like to kick those plants up into high gear and would be worried that my fish die with PH swings... I'm using excel now, so I suppose I could just sit back and see how that works.... does anyone have any thoughts or advice on this? It seems that high PH, really soft water is a strange combo perhaps?

 

[shawmutt]

It seems that high PH, really soft water is a strange combo perhaps?

With a regular aquarium setup, yes it does. What exactly is your carbonate hardness? gh?

As far as using co2 with soft water, it can be a problem if your plants or fish don't like the acidity. Depending on how low your buffer level is in your water, it could cause a pH crash that will be fatal to your fish and may even kill your plants. However, with water of a pH of 7.8, I think you'll find your water has sufficient buffers to counter the effects of co2. Additionally, the Hagen packets have baking soda in them, with also curbs the effect from the injected carbonic acid. My formula for my 2 liter diy system was 6 cups of water, 2 cups of sugar, 1 teaspoon of baking soda, and one teaspoon of baker's yeast. I had a soft water tank, the kH was 2-3, and I didn't have any problems using my formula (the formula was given to me by someone in this forum, BTW, so it's not really MY formula ) HTH!

 

[medge00]

kH is about 1.5 degree hardness, gH is about the same I believe...That's straight tap water with the regulator... I can bring the water down a tad w/ RO water, which would relieve the PH a little but then its still really soft water... this is all starting to get really frustrating to me. I've done a bunch of research but still don't know what to do!

 

[betowess]

You could try putting some oyster shells or crushed coral in a bag in your filter to bring up your KH, but unfortunately it will raise your PH a bit too.

Seachem's equilibrium will bring up your GH if you need it. I have really soft H2O too, but my ph is below 6 out of our well so I use an alkaline buffer to raise my Ph and KH. Seachem's Equilibrium can bring up GH, with almost negligble raise in KH.

The main problem with water as high as 7.8 Ph is no matter how much C02 you put in the tank, even pressurized with a reactor (and a hagen or DIY won't make a dent in it either), you won't experience much absorption of dissolved CO2. For a planted tank you would be better to get closer to 6.9 or a 7Ph if the fish you have can handle that pH.

Planted tanks generally do best with a PH near 6.9 and 15 to 24 ppm of dissolved CO2... There are some plants like Val, however that prefer more alkaline water.

Hope this helps. Betowess

ps...Here I've copied a chart which shows what happens to dissolved CO2 absorbtion relative to a tanks carbonate hardness (aka its KH) versus its pH ...

The following chart shows dissolved CO2 levels in ppm for a range of
KH and pH values:

degrees KH
2 3 4 5 6
+------------------------
6.6 | 15 23 30 38 46
6.7 | 12 18 24 30 36
6.8 | 9 14 19 24 28
pH 6.9 | 7 12 15 19 23
7.0 | 6 9 12 15 18
7.1 | 5 7 9 12 14
7.2 | 4 6 8 9 11
7.3 | 3 4 6 7 9
7.4 | 2.4 3 5 6 7
7.5 | 1.9 2.5 3.5 5 5
7.6 | 1.5 2 2.5 3 4
7.7 | 1 1.5 2 2.5 3
7.8 | 0.9 1.1 1.5 2 2
7.9 | 0.6 0.9 1 1.2 1.6
8.0 | 0.5 0.7 0.9 1 1.2

 

[medge00]

so how do you think seachem's acid buffer would do? in theory, it would work reasonably ok wouldn't it?

 

[Guest]

shawmutt,

Additionally, the Hagen packets have baking soda in them, with also curbs the effect from the injected carbonic acid.

You are using the Hagen system wrong. The baking soda is supposed to go into the reactor vessel and not into the tank. It's used to provide an basic environment for the yeast. If used properly it never enters the tank water and has no effect on the tank water.

medge00,

I find it hard to believe that your tap water has a pH of 7.8 with a kH and gH of only 1.5 Are you testing the pH of your tap water after it has set for a few hours or right from the tap? Do you know if your water company is buffering the water? Have you tested the tap water for phosphates? To really help you with your problem I need to know your tap water readings after the tap water has set out over night. pH, gH, kH. Don't add any buffers or regulators.

I just checked the Santa Barbara water quality report and I think you might need new kH and gH test kits. Or take a water sample down to the LFS and have them test it. The water quality report is showing much harder water than what you have. Do you have a water softener in the house?

 

[medge00]

I was testing right from the tap also and the results were the same. I've tested both right our of the tap and let it sit overnight. I'll take a sample to the lfs today or tomorrow to have it checked. I don't think there's a water softener in the house, but then again, I rent and my landlord is very difficult with even the easiest of questions...

 

[shawmutt]

You are using the Hagen system wrong. The baking soda is supposed to go into the reactor vessel and not into the tank. It's used to provide an basic environment for the yeast. If used properly it never enters the tank water and has no effect on the tank water.

I was incorrect. I used a diy system, and I did put the baking soda in the soda bottle (reactor). What it does is stabalize the pH in the reactor to keep the acidifying water from killing the yeast. It does not affect the pH of the tank water. Thanks for calling that to my attention!