Water change frequency and automation

[nycman]

I started a 180G tank last summer and have been doing large weekly water changes - usually and never less than 55G, but sometimes 110G. My tank seems to have really turned a corner in recent weeks, with bad cyano outbreak eradicated and fish and corals now growing/spreading.

My system allows for easy large scale water changes as my return pump is PVC plumbed into my house drain so I can completely empty the sump into my sewer in about 60 seconds with a button on my iphone. And then another button and am filling it from a can of new salt water. However, I do have to manually set 4 ball valves to control the water flow direction, and shut my return on and off for all this to happen.

I have been reading that smaller and more frequent water changes are more healthy. Makes total sense. Am considering an automatic system. The Genesis looks like a good system.

Here is my question. With large water changes I make RO/DI water daysor as much as a week beforehand and let it sit still, and then add salt mix and use power head to mix it and use it right away. So I am not storing mixed salt water for more than a few hours - just enough time for it to mix properly and reach my target salinity. With these autosystems, or a manual but more frequent (daily), but small change, it seems I would need to keep a large volume of mixed salt water always on hand since I am away from home 4 days every week. I have heard that mixed salt water sitting in reservoirs does not last that long. So how does this work with more frequent, smaller changes, whether manual or automatic?

 

[avery155]

Keep the new salt water flowing with a pump and a heater. Make sure there is surface agitation to keep pH stable.

 

[nycman]

This is my freshwater planted tank adjacent to the reef tank. Here I am doing 100% changes per week - usually 50% a day each weekend. Would definitely love to make these smaller and more frequent as it hosts Discus.

 

[Member No. 1]

I do 3 gallons/day on a 80 gallon tank.
I premix my salt, plain old Instant Ocean, and it sits unheated and without circulation. I keep 55 gallons of RO water, 55 gallons of DI water, and 100 gallons of premixed on hand. All unheated. Never had an issue.

 

[mcgyvr]

No offense but it sounds like a waste of water/salt/money.

Changing what amounts to 10% of the tank volume every week is usually plenty on any system unless there is a clear reason to do so..
You can certainly change as much as you want but it really is just a waste..

Technically larger water changes are more efficient too..
http://reefkeeping.com/issues/2005-10/rhf/

Also mixed saltwater can also be stored for quite a while... There has been some speculation that certain salt mixes that may contain vitamins and organics like reef crystals may have limited storage life but there is no proof to that nor will the salt manufactures agree with that either (well I asked the makers of reef crystals and they said it can be stored indefinitely anyways)..