PH / Nitrate question

[ekean45]

I have a question concerning a swing in PH / Nitrate drop.

Here is the set-up I have in a 60 gallon SW fish only tank started on 12/3/11:

• About 2 1/2 inches of live aragonite sand
• About 20 pounds live rock and 40 pounds base rock (becoming live)
• Marineland Emperor 400 BIO-Wheel Powerfilter (made for a 90 gallon tank)
  
• Heater – Fluval M200
• Reef Octopus BH1000 protein skimmer
• AA Aquarium UV sterilizer – 24Watt
• 2-18” 50/50 Actinic bulbs - 1 per canopy
• 2 powerheads
• Small Refugium from useless Cyclone 100 - live rock, live sand, ½ lb calerpia - T8 18" full spectral bulb

To assist in lowering nitrates, On 3/3/12 ago, I added NPX Bioplastics to one side of my filter and on 3/10/12, I turned a crappy cyclone 100 protein skimmer into a small refugium. I understand that the refugium is pretty small and does not do a ton of work to remove nitrates but it is better than nothing. I also was told that you can see a PH swing from having the refugium lighting on 24/7.


Here are the results of the tests over the last 2 weeks. I did a water change just before adding the refugium on 3/10.



Date Salinity PH Amm Nitrite Nitrate

3/10/12 1.023 8.30 0.00 0.00 10.00
3/11/12 1.023 8.30 0.00 0.00 10.00
3/15/12 1.024 8.30 0.00 0.00 20.00
3/18/12 1.024 8.10 0.00 0.00 5.00



My questions on this is I can see that the 3/18/12 PH may have had a swing due to keeping on the lighting 24/7, but is it possible that my nitrate levels dropped this drastically without a water change from a small water change and adding the NPX Bioplastics?? Could there possibly be an issue that would mask or cause a nitrate level to drop like this?


Fish coloration look great and they are very active. When I come to the front of the tank, most of the fish come to greet me (obviously expecting food), and when I do feed them, they devour what I put in the tank within 2-3 minutes - I feed them 2-3 times per day with a mix of different foods - Nori, cyclops, mysis shrimp.



Is this too good to be true?


Thanks.