So, I was recently reading in RC and I have to say I came across an article that literally changed my thinking in regards to corals and water quality. I thought I would share my experience because like so many others, I did not completely understand the concept. Please corect me if I am wrong in some information. I just want to help people who might be having the same issues.
In my tank I try to keep the nutrients in check and run a clear, clean system. My previous experience and limited knowledge told me that if algae occurs I have to much PO4; therefore, feed less and maintain less nutrients. Yes, if you have effective methods to remove water soluble PO4 then this will occur. This information that I did not know was that PO4 comes in different forms in the aquaria. This leads me to my problem.
My previous knowledge told me that SPS and other corals require very low amounts of PO4 and NO3. This is VERY low, but not 0. So I would test my tank and see that I had .08 ppm PO4 and undetectable NO3. I was proud of the lower levels, but this cause me to focus on keeping them low and not understanding the nature of the values. I feed very little and because of it had horrible coloration in corals, slow growth rates, and "just ok" fish
As stated by previous reefers on RC, the PO4 we test for is water soluble. The PO4 we FEED is organically bound (I believe this is the correct term). We do not test for the PO4 from the food we feed we test for PO4 that becomes saturated in the water. I thought that we tested for a simple number that was just PO4 and all of it. After reading the article I came to 2 conclusions. Because I believed PO4 was only one value and only related to the food I feed to the tank, I would feed less (a lot less), to keep numbers/algae manageable. Because I was ONLY relying on the amount of food I was feeding to manage water soluble PO4, I was causing harm to the inhabitants of my tank by starving them.
Now, the last week I have been feeding more and I can tell you that in just a week I have seen a dramatic difference. Not only in fish, but corals as well. I feel stupid from this simple error and I am just trying to help other understand the balance we must try to meet. I am not saying to dump food into the tank, but what I am saying is that you have to FIRST meet the dietary requirements of the tank, and tailor your nutrient export methods the amount of food you provide. Try not to change feeding lower than what your inhabitants need to survive to manage PO4 and NO3, but find better (or fine tune) export methods. Again, for some more experienced reefers this seems like a no brainer, but I somehow missed this in my reefing journey.
I have never vacuumed any sand bed, only a BB tank I have ran; however, I have started to do this with every water change. water soluble PO4 comes from the rotting matter that ends on the sand bed. For my tank (only 1-2") sand bed I am going to utilize manual vacuuming to control excess PO4. If this is not enough I will use GFO to help absorb the nutrient.
I hope I have written this in a correct and informative manner. If some newer reefers have more questions just search in reef chemistry forum for PO4 and you can find the discussion.
Take care and happy reefing!!!
