小弟於前2週量了NO3,居然高達100
What kind of test kit?? You sure you used it correctly?? You sure the test kit is not some outdated products?? How long has this tank been set up?? With a mature system, one might need to dilute the test kit in order to get a lower level reading.
小弟總水量約為300公升
So you have a 120 gallon system, like the ones I have. How much live rock you have in it. Been visiting the Taiwan site for a while so I am going to ask you this question. You sure you got the live rock?? You might purchased the base rock instead.
隔天小弟狠下心把底部缸的砂(非活砂)全都清出來清洗一遍
What is the purpose of this?? Why put sand in the sump?? Filtration purpose?? If that is the case, then forget it. You need a sump that is either 2X larger than your main tank for this to work. Let's assumed you do have a sump that is 240 gallon, the depth of the sand bed needs to exceed 8". The size of the sand should be sugar grine and needs to be live.
NO3的來源是否是底部缸裡的砂(粗的)造成的
yes, since you do not have enough surfacing area, and the sand is not "Live", this compartment became a waste build up facility.
是否要把砂全部移出
I would strongly suggest you do so.
還是小弟必須添購一台硝酸鹽化除器
I see no points in this gadget.
既然有大量活石,為何NO3又會如此高呢
Again, you sure you got the live rock and not some base rock which is deseier and lack of the porous surfacing area?? If you did in fact got the live rock, do you have sufficient amount to support the system you have??
若小弟不把底部缸的砂移除,然後添加一台硝酸鹽化除器,能降低缸中的NO3嗎?
Not really. The current set up will work against each other. That means your sump's sand bed will continue to produce Nitrate by the trapped debries, un-eatten food, fish waste, etc... and the Nitrate reducer will contintue to take out the nitrate at its capacity. The nitrate reducer will continue to take out the nitrate from the sand bed and eventually, overwhelmed by the nitrate produced by the main tank and the sump and stop working.
Now, here is my question to you. Do you have a pre-filter sponge in your overflow??? How can the un-eatten food got into the sump?? Do you have any sand in the main tank?? If yes, what is the size, depth and base material for the sand?? You never mention skimmer? besides the live rock, what other means of filteration do you have? You have about 11 fish, what size are they?? You have the sump?? What is the size of this sump?? Seemed to me you have a lot of problems with your set up. Suggested by the LFS again?? I can feel your pain. Take care and HTH!