I began to observe an increase in algae so tested to confirm my suspicions
My little reef was running generally with decent levels:
Nitrate 0.5
Phosphate 0.05
But these parameters had now changed:
Nitrate 0.2
Phosphate 0.34
I was a little confused as Nitrate had gone down but Phosphate had spiked as expected. I made sure I continued with my normal regime thinking my biological system would adapt and deal with this spike. This started to be the case as the parameters showed a drop in phosphates to 0.045, and stable nitrates, so things were going the right way.
Unfortunately, when doing the rescape I had swapped some rock with another aquarist which unfortunately introduced Bryopsis. I treated this using fluconazole, with great success. Whilst undergoing this treatment I was conscious of the amount of dead and decaying material that would be in the water column. I introduced a new filter sock, which I began to clean every few days. I also tried to keep the areas of my sump, other than the refugium, clean and cleaned all of the pumps and pipes as best as I could. Apart from this I continued my usual regime of cleaning and weekly water changes.
Over the last couple of weeks I noticed some changes in my little reef. Nothing significant, but enough to make me think that nutrient levels had dropped. So, to confirm my observations I did a couple of tests.
Nitrates 0.02
Phosphates 0.008
Wow I have accidentally achieved an Ultra Low Nutrient system without using any any expensive kit or chemicals. My tank is pretty well stocked and the fish fed several times a day.
These levels are a bit too low for my liking but I think in time they will rebalance themselves.
It certainly shows that my stocking levels and bioload are not too high, I am not overfeeding and my natural cleaning and filtration system is highly effective and adapts to the conditions within my reef.