Epiphyte
Member
I've had this nagging question in the back of my mind for some time now, I'm hoping the combined wisdom of UKAPS may help me make better sense of it.
Convention says that with a high tech aquascape, I must perform a 50% water change weekly, which I do, give or take a day or so. My question is though... why?
If I look at my tank, it's roughly 160 litres of RO water (Oase 90P), remineralised to a TDS of 120. It has large amounts of plants, mostly fast growing stem type. Fish stocking for the aquarium size would probably be classified as low, roughly 30 small tetras, a dwarf gourami pair and a flotilla of Red Cherries. I lean dose APT Complete and the whole thing gets turned over with an Oase Biomaster Thermo 600, filled up with excess amounts of Seachem Matrix. None of my hardscape choices affect water quality or chemistry either. For all intents and purposes, the water is immaculate and, minus a small amount of BBA on the hardscape, is completely algae free.
So why with a well maintained and mature aquarium, with plants exporting so many of the nutrients and so little coming from waste, do we do this unusually large water change? If I get to the 7 day mark, everything bad reads zero and nitrates are low, what am I actually exporting via the water change?
I'm not expecting there to be double blind peer reviewed studies over this, but anyone I have ever asked sort of shrugs and says they aren't sure why we really do it. Are we doing it because it's convention? Because there is something in the water we don't traditionally measure that we're exporting? Or am I just pouring perfectly fine water down the sink every week?
I appreciate that when something is going wrong, a big water change is the first thing to do, but this is all assuming a well operating tank.
Interested to hear peoples thoughts.
Convention says that with a high tech aquascape, I must perform a 50% water change weekly, which I do, give or take a day or so. My question is though... why?
If I look at my tank, it's roughly 160 litres of RO water (Oase 90P), remineralised to a TDS of 120. It has large amounts of plants, mostly fast growing stem type. Fish stocking for the aquarium size would probably be classified as low, roughly 30 small tetras, a dwarf gourami pair and a flotilla of Red Cherries. I lean dose APT Complete and the whole thing gets turned over with an Oase Biomaster Thermo 600, filled up with excess amounts of Seachem Matrix. None of my hardscape choices affect water quality or chemistry either. For all intents and purposes, the water is immaculate and, minus a small amount of BBA on the hardscape, is completely algae free.
So why with a well maintained and mature aquarium, with plants exporting so many of the nutrients and so little coming from waste, do we do this unusually large water change? If I get to the 7 day mark, everything bad reads zero and nitrates are low, what am I actually exporting via the water change?
I'm not expecting there to be double blind peer reviewed studies over this, but anyone I have ever asked sort of shrugs and says they aren't sure why we really do it. Are we doing it because it's convention? Because there is something in the water we don't traditionally measure that we're exporting? Or am I just pouring perfectly fine water down the sink every week?
I appreciate that when something is going wrong, a big water change is the first thing to do, but this is all assuming a well operating tank.
Interested to hear peoples thoughts.