Hi PDSimon,
In one of your replies above, you stated that WD said that nitrates are present in the substrate. The gravel cleaner I ordered as seen
here removes trapped dirt and presumably nitrates along with it.
I know I shouldn't be worrying about the nitrate level given that I don't have any fish yet but I was wanting to try the gravel cleaner out and also do a 90% water change to see what effect it has on all the water stats. I know ammonia and nitrite would go to zero and my PH will drop to 7.4 once I re-fill the tank with dechlorinated water, BUT I don't know what nitrate level I will achieve and what effect disturbing the substrate will have on the beneficial bacteria. Due to being in the unknown I was going to do an early water change and clean the gravel and make a log of the water chemistry stats after wards so I have a good idea of what to do should I have a build up of nitrates (or other toxin) when the tank is stocked. I do plan to stock the aquarium on friday so I guess I'm getting a bit anxious about doing everything perfectly.
Fish waste is what causes the nitrates to be in the gravel, you don't have any fish, so a gravel vac isn't needed. If you do a 90% water change, you can take it from the top of the tank, and as long as the water is de-chlorinated, there won't be any damage to your bacteria.
Doing the 90% water change will give you a nitrate level similar to that of your tap water. My tap has 10-20ppm (it's impossible to tell the difference between those colours on the chart).
The best way would be to get some Bolivian rams along with whatever stock you plan on getting on Friday as these are more tolerant, have a temperature of 26-27C and monitor how the nitrates build up over a month or so with your regular water changes.
Then you could ask a lfs about there water stats and if they have the GBRs in similar Ph and hardness to your water then they would be a good choice. 7.4 and 9dKH isn't perfect, but it's good enough.
If you think your nitrate level is too high, you can buy filter sponges that remove nitrates to add to your filter, think about planting your tank if you wanted, or do more water changes.
Using your tap water will be much better as the Ph will be close to that of the tank, and you won't have to worry about it swinging when you do water changes.