Expert: Chris Robbins - 5/22/2007

Question
My son is setting up his third tank and has decided to use aquarium sand instead of gravel this time.  We have heard that it is ok to use and then also that it is not a good idea.  The water, on filling the tank (35 gallon), was chemically balanced but now has started to drift to higher PH and has higher Nitrate and amonia levels.  The tank has been set up for two weeks and only contains the sand and lots of live plants, drift wood and some larger rocks.  We are going to try a 3/4 water change tomorrow and then see if the levels creep back up again.  Do you think the most likely culprit is the sand?  This is the first time we have used live plants in a tank as well but I find it hard to believe that plants would cause this issue.  Thank you for taking the time to give this a go...Kathy

Answer
Hi Kathy;

Don't make any water changes. The only time you need to manually lower ammonia is to protect fish in the tank. The toxins aren't going to harm anything at all if there aren't any fish. With the wood, rocks and plants in there the organic material on them has added an ammonia source to get the cycling process started. It's actually a good thing at this point and is called "fishless cycling".

Monitor the levels over a period of 4 to 6 weeks and they will stabilize on their own as beneficial bacteria colonies continue to develop. Don't add fish until the ammonia (NH3) and nitrites (N02) are "zero". Nitrates (N03) can be as high as 20 to 40 ppm. It's the end result of your biological filtration process. It can only be removed by making water changes.

The pH may be a problem but the driftwood may lower it over the next few weeks. If it is around 8.0 and doesn't drop, it may mean that the sand has too much calcium in it. Many sands have crushed shells or coral. They leach into the water and cause it to harden. The pH then rises. One solution if it continues is to only keep fish and plants that like a higher pH. Another is to remove the sand.

Let me know if you have further questions...

At Your Service;
Chris Robbins