I totally agree that water changes are the single most important thing we can do for the well being of our tanks. I change 20 g per week on my system and believe that if my water quality was great to start with, no negative effect will be felt. In doing so I am relenishing the elements, minerals, and other goodies in my salt mix.
I am also in complete agreement with Shaun regarding the impact of water changes on the bacteria in the tank...if your tank is healthy is no impact. If you haven't been doing water changes, start slowly and increase the gallons changed and frequency of the changes over time. This is not a zero to 60 in 5 seconds kind of hobby.
It's easy enough to match the temp, salinity and PH and I fail to understand why folks wouldn't be doing more of them on a regular basis.
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That said I'm really here to post some info & pics on my ATO...this info was originally posted back in January..rather than a link, here is most of the original post:
The discussion was about float switches I had gotten from Aquahub..
I have these same float switches in my ATO system and they are mounted to brackets made from eggcrate. Two of the switches are in my fuge and the third is in the top off tank. Three switches are used so the fuge will neither underfill or overfill (one is mounted upside down & the other right side up) and the one in the top off tank is so the pump won't come on in the event that tank is too low on water.
The relay was used due to the safety concern. I used a small pump (if I recall it was about 120gph...actually a fountain pump) and a 12V power supply.
The power supply came from
www.jcaquatics.com
It is the 12v adjustable power supply. Shipping from JC Aquatics gets to me overnight (same zone), city might be 2 days.
The instructions from Aquahub suggest a 9v 300ma power supply, but that is incorrect as the relay actually requires 12v so it doesn't prematurely die...just an FYI on that part!
Edited..
The system works great!! I use a 10 g tank for top off water and only have to refill once a week (on a 75g system w/30 g fuge).
1st pic shows how the bracket and how the switches 'sit' on the baffle in my fuge.
2nd pic is of the float switch mounted in my top off tank (the relay is wired to an extension cord
using heatshrink and it is out of the pic (and harms way!) to the right side of my top off tank.
The 3rd pic is a better view of how the 2 float switches are mounted in the bracket Psycho Graphic
made (that bracket was made for his tank, so it was done in black).
The top off water was plumbed using 1/2 pvc and goes directly into the last chamber of my fuge where my return pump is. When the tank requires replacement water the pump comes on for a very short period of time, and does so multiple times per day.
The top off tank is in the room next to where my tank is and sits on the floor inside of a cabinet. It rises about 18" up and then travels horizontally about 1 1/2 feet and back down into my sump.
The only downside to my system is when I forget to shut if off while doing a water change...and it keeps trying to refill that last chamber in the sump upon system start up. Aside from that ...I love this this thing!!
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