KH / GH / PH question

[SBA]

Hi

I've recently upgraded tanks to a 240litre (~60 US gallons).

I moved my old tank's filters, gravel and plants into the new one and filled up with dechlorinated tapwater.

Everything is fine in terms of ammonia = 0, nitrite = 0, nitrate < 5.

in the tank: PH = 7, KH <= 1dKH (17.9ppm), GH = 5dGH (90ppm).

from the tap after gassing off: PH = 7.5, KH = 2 dKH (36ppm) and GH = 4dGH (70ppm).

substrate is flourite / gravel mix, moderately planted (no CO2), decor some rocks (don't affect PH), coconut caves.

incumbents are blue tetras, harlequins, cories and 2 SA puffers.

does this sound 'normal'? should I be thinking about raising the KH using crushed coral or simlar? if so what to, and will it affect the PH much?

thanks for any opinions / replies.

Ade

 

[OrionGirl]

My guess is that you will want to push that KH up a bit. I think 3-4 is in the stable range, and anything less will be prone to crashes. As to raising it--baking soda and crushed coral are the best bets. Baking soda can be added to your water before changes, and a baggie of CC in the filter will work for the long term. The problem--it will boost the pH a bit. How much depends on how many acids are in the tank to burn through the KH. I would start with a small amount of crushed coral, and see how that goes. Make all changes slowly, so your fish have time to adapt. If the pH goes to high while raising your KH, I think that CO2 supplementation might bring it back down without affecting the KH--but check with one of the more chemically enabled members before taking my word on that.

 

[SBA]

thanks OrionGirl,

that's sort of what i'd figured. what is confusing me is that despite the move to a new tank with 'fresh' water the KH is still lower than the tap water, seems like in 3-4 days the KH has halved.

i'm thinking that KH supplementation is the way to go.

Ade

 

[OrionGirl]

The KH is lowered by the biological processes taking place--the bacteria and fish both contribute to it's decline. Plants will utulize the KH from the water, too. My tanks with more anubias and java fern seem to go through more KH than my tanks with lots of stem plants--might be unrelated, though. I bet if you had the water just sitting in a glass, covered to prevent evaporation, it would remain pretty steady for a long time.

 

[SBA]

yeah - i'm sure it is 'something' going on in the tank, incidentally (maybe?) i have both anubias and java fern in the tank. not enough of either i don't think, to make much of a difference.

i'll give the CC 'in a baggie in the filter' method and check the KH regularly, i'll try to stabilise it at 3-4 dKH and see how it goes.

thans for the responses.

Ade