[FishLover61]

I just checked my water and the first test was ph. It had been at a steady 7.0 since startup a week ago, now it's around 6.3. For the first time the ammonia level has moved from 0 to 0.25. Nitrate and Nitrite are still at 0.

I haven't done any partial water change on this new tank yet and I have a few danios and tetras. Is it time for a partial? If so, what would be considered a partial in a 46 gal tank? Will the partial help with ph, or is that a matter of getting a buffer?

Thanks so much!

 

[Thoth]

The size of the water change will depend on the size of the tank and what you are trying to accomplish with the water change. You want to have ammonia levels as low as possible and at all costs keep it under 1 ppm. If your tap water has 0 ppm (not all tap water is 0 ppm) of ammonia and you do a 50% water change, you cut the current measurement in the aquarium in half. Your .25 ppm reading becomes .125 ppm. Personally, I do 50% water changes because it is easy to calculate the end results.

For the pH, you should know that it will change through out the day. The pH change is gradual and as long as it does not drop out of their acceptable range they will be fine . You will want to measure the tank at the same time of day to get a comparison of a change over a period of time. It is also natural that the water will become more acidic over time; Nitrification, changing of ammonia to nitrite, will acidify the water.

Try to get some live plants in the tank as this will reduce the ammonia waste in your water. Also, shoot for changing 100% of the water per month in at least 2 water changes.

 

[Thoth]

Also, you can measure your KH as this buffers the pH. With a low KH you will notice more of swing in the pH. You can try to raise this with chemicals but I would advise that you do not use any of the buffer chemicals if you are new to the hobby.

 

[AbbeysDad]

From the very beginning a weekly water change of 25% to 50% is a good practice.
In an established tank (6 months) IF you have lots of plants, high levels of filtration/purification, good tank/filter maintenance and watch feeding closely, WWC volume can be reduced slightly. But right now, you might do 20-25% twice weekly until you're convinced that the tank has cycled.

 

[Byron]

I agree with what's been posted. You are actually in a lucky spot, with water on the acidic side (pH below 7). In such conditions, ammonia changes to ammonium which is basically harmless to fish. So the establishment of this part of the cycle (the Nitrosomonas bacteria will use ammonia/ammonium whichever is present) will not pose a problem to the fish. The same can't be said of the nitrite however, which is also lethal.

Live plants, even some floating plants, will greatly help this. Daily water changes if nitrite is above zero are advisable. Even though fish may live through it, there is almost always permanent damage that will surface down the road.

While we're on the topic of water changes, here is some data that will go into all this a bit more:
http://www.tropicalfishkeeping.com/freshwater-articles/regular-partial-water-changes-117205/

And welcome to Tropical Fish Keeping forum.:-D

Byron.