Auto water change - what's best?

[MrsReefK]

If you were to setup auto water change (via apex), which do you think would be better, 30 gallons in increments throughout the week. Examples: every 4 hours dispose of one gallon and then bring in one fresh gallon of mixed saltwater.

Or, 30 gallons at one time each week?

Is there an advantage/ disadvantage to both scenarios?

[MrsReefK]

For the record, this is an in house dispute that needs some light to it. I vote for a little at a time, I want to take the tank water that's being disposed of and drain that into the QT. Then QT will dispose of that amount of water to the drain. Jeremy (husband) says that a mass amount at one time is a better WC.

[skeeter_ca]

It is said that stability is the key. Small more frequent changes would cause less of a swing in all parameters. Not to say 1 large change does any harm. People have been doing it both with success ways since aquarium keeping started.

Oh well, guess that didn't help much!

[goldencoralfarm]

I would say anything that you feel comfortable with (time wise). Changing small amount of water each day will guarantee the water stability. But 30g water change through out a week will be less than actually water change of 30g all at once.

[SeanRB]

I am of the belief that you match the parameters of your tank water, and empty a larger amount out and replenish it with water that has the same Ph, Calcium, Alk, temp and salinity. If you do constant water changes or very frequent small changes, you are removing some of new water with old.

"The Solution to Pollution is Dilution" take out as much pollution as practical, and dilute it with a greater amount of "perfect" water. By "perfect", I mean perfectly matched.

[slief]

I have an Apex and I use the Genesis Renew. My Apex serves as my failsafe for it even though the Renew is pretty much fool proof and always 100% spot on accurate with no calibration needed. 1 Gallon in and 1 Gallon out. There is no better device for automatic water changes. You could use a Dos which works well but the Renew allows you to select your water change volume from 1 to 99 gallons and select whether you want it daily, weekly or continuous (all at once). It can change a gallon of water in under 3 minutes so if you want to do a large water change, it's as simple as selecting the amount and hitting start.

I've been using the Renew for over 3 years and used a litermeter 3 for a couple years prior to that. For over 20 years prior to that, I did manual larger weekly water changes and can tell you from first hand experience that daily water changes are less stressful on the tank and it's inhabitants even if you matc everything perfectly. And, while you may be removing a small portion of the new water with each change, it's a negligible amount. The upsides far outweigh the negatives and to be honest, I can't think of a single negative. Like I said, less stress on the tank, consistant water quality instead of water quality degrading even slighly over he course of a week etc. You can get away with less water being changed per month because the waste isn't building up over a period of time but instead the water quality is consistently being maintained and in this hobby, consistency is probably one of the most important things. Especially when it comes to water quality.

My very heavily stocked and overfed tank maintains perfect water quality and with much less water being changed. I change out less than 20% a month despite having over 60 fish. Many of which are 8" plus large tangs that are overfed 3x a day. There are absolutely no downsides to daily water changes. Only upsides in my experience and there is nothing on the market that compares to the Renew for water changes. Nothing.

[MrsReefK]

I am of the belief that you match the parameters of your tank water, and empty a larger amount out and replenish it with water that has the same Ph, Calcium, Alk, temp and salinity. If you do constant water changes or very frequent small changes, you are removing some of new water with old.

"The Solution to Pollution is Dilution" take out as much pollution as practical, and dilute it with a greater amount of "perfect" water. By "perfect", I mean perfectly matched.

Hey Sean, I see where you are coming from. We wouldn't put the 'fresh gallon of SW' in until after the old gallon has been removed and disposed of. Does that make sense? This way there shouldn't be any dilution and no removing new water.

[Member No. 1]

I'm using a Neptune DOS for daily AWC of 6 liters (~1.5 gal). From 12:00am to 10:00am it removes the OSW, then from 10:00am to 8:00pm it adds NSW. This way I'm not adding new while removing old. My sump is big enough that the level change during the day doesn't effect anything.
As stated, this will keep the water more stable, than letting impurities build up over a week or month. Also will keep trace elements that NSW add at a more constant level.

[bearpeidog]

Good resource for water changes: http://www.reefkeeping.com/issues/2005-10/rhf/index.php#14

[slief]

Hey Sean, I see where you are coming from. We wouldn't put the 'fresh gallon of SW' in until after the old gallon has been removed and disposed of. Does that make sense? This way there shouldn't be any dilution and no removing new water.

That is one of the advantages of the Renew. One gallon is pumped out of the sump and the holding tank at the same time. Once the metering bins are full, the water is then released to the sump and waste water drain location. You aren't removing any of that 1 gallon of new water while the water change is taking place. In my case, I have my Apex setup so that the ATO float switches have to sense a low water level for 3 minutes before activating my ATO pump. This insures that the 1 gallon water change is complete and the ATO is never activated because of the AWC. Then again, I have a huge sump and a gallon of water won't really impact my ATO. Even if it did, the extra fresh water won't impact my salinity or sump level and it will evaporate anyway.

[Tarawa]

I'm doing AWC with a dos, changing 10g a week. I dont think theres too much concern over it eating too much of the new saltwater with this method. I have the old saltwater intake positioned behind a stream pump in the sump, and the new saltwater output positioned in the return pump area. It exchanges 40ml every 10 mins in this fashion. A nice thing about doing it slowly is you dont need to worry about matching temp, or if the salinity is off. I am also spiking my new saltwater with more magnesium to offset the coral's uptake. Where as doing larger batches all at once, you'd need to match some what closely and heat the water. (unless your tank is really large and swapping 1g wont affect much)

But all said and done, which ever method you choose, you cant go wrong, AWC is amazing =D

[perkint]

"Better" in this case depends on the context. Better for stability? Lots of smaller changes. Better for reducing pollution/increasing trace elements (or whatever)? A single larger change.

If you do say 1g in and 1g out, next time you change, you remove some of the first gallon. By the time you are adding the 30th gallon, you are taking some of all of the previous 29 out as well. The percentages are not huge - you would have 5.7% better gain/reduction (whichever you were after) doing a single change of 30g compared with thirty 1g changes.

But, as said, for stability, lots of smaller changes are much better.

As always in this game, best depends on what you are trying to achieve.

Tim

[MrsReefK]

Thanks everyone! We decided to go forward with changing a little amount overtime to change a total of 30 gallons per week. We will be laying out the entire AWC setup in our build thread once it's up and going. Thanks again.

[Marshall7199]

I am no authority on this subject but common sense tells me small is better for stability reasons.