Water For Discus

[justandy333]

Im a little new to this forum but im after some advice about adjusting water conditions.
I own a 260L (55 gallons approx) bow front aquarium.
3 discus (unfortunately 3 have died) , 5 rummy nose tetras, 7 cardinal tetras.

The aquarium has RO water in it which has been treated with remineralising powder every water change.
The problem Im having is getting to grips with and understanding the relationship between PH, GH and KH.

Its my understanding that discus require a ph of about 6.5 - 6.8 Slightly acidic. The GH needs to be below 50ppm. The KH needs to be higher to prevent the PH swinging too much.
The problem is raising the KH. Its around about the zero mark. So the ph fluctuates easily.

Recently the ph crashed to about 5.5. The suspected culprit for the discus deaths. So to compensate i added coral rock granules into the fiter to bring the ph back up. But the GH has climbed dramatically. The KH is unaffected. I need to know how to increase the KH to bring stability to the aquarium.

Any help would be much appreciated. If my understanding of water chemistry is wrong, feel free to correct me.

 

[mike os]

OK

1, discus will be OK in water from Ph4 - 8, mine have frequently been lower ( ...nearly 3, not that I advise it) ideally Ph 6-7.8.

2, Gh and Kh are almost irrelevant for tank bred fish. For soft water a gh about 5 and kh4 is good, but can be difficult to maintain.

3, the remineralisation powder will probably not have a buffering agent, bicarb works well.

4, If your tap water is about ph<7.6, gh<8, kh<8 then you can probably do away with the RO altogether ( depending on where you live), or use a percentage of tap water to remineralise the RO....this generally gives better results than powders IME.

5, Stable water parameters are far more important than any specific value, so if you get it witin the above range and can keep it constant that will be far better than messing with it.

 

[justandy333]

Thankyou for the info.
You mentioned Bicarb? By that do you mean Sodium Bicarbonate? Same stuff thats in Baking Powder? Wouldnt that intefere with other levels in the tank?
Just checking the tap water levels as we speak/type lol

 

[rabbut]

^^That be what he means, Bicarbonate of Soda

I'd say you are half right with your "caurse of death". A pH crash isn't a direct killer if the pH stayed above 3, there has been research posted before surgesting that the internal pH of a fish can change from pH7 to pH 4 within 15 minuites if the outside pH also moves by that, so the maximum length of time for pH shock is theoretically 15 minuites... I'd put the COD down as messing with water chemistory when you don't know what you are doing with it. Sorry if this sounds blunt, it is not intended to sound so, but when it come to water and the pH/KH ballence, you need to know what you are doing before you try to alter it. If you do not, leave it well alone.

What is the GH, KH and pH of your tap water and neat (not re-mineralised) RO? Also, what's the TDS reading of your RO?

All the best
Rabbut