AWC question for the experts?

[Reefmonsters]

So I am in the middle of getting my AWC set up on DOS, and in the middle of doing this I am thinking during the change all I am doing is diluting my new water and pulling it back out through the change? Am I thinking about this correct or am I missing something?

 

[sunken3]

So I am in the middle of getting my AWC set up on DOS, and in the middle of doing this I am thinking during the change all I am doing is diluting my new water and pulling it back out through the change? Am I thinking about this correct or am I missing something?

i do this with the DOS as well. yes you are thinking about it correctly. this is really just a way to "maintain" your tank. (i do 3-5 gallons a day (on a 300). you can use the DOS to do up to 30 gallons in 24 hours (but i wouldnt obviously recommend that often). if you are looking to reduce nitrates/phosphates, this is not really the way to go.

 

[Gablami]

I would suggest you check out this informative article by RHF.

http://reefkeeping.com/issues/2005-10/rhf/index.php

Daily or continuous water change is just about as effective as larger less frequent water changes, given the same total volume changed.

snapshot of one of many diagrams.

 

[sunken3]

I would suggest you check out this informative article by RHF.

http://reefkeeping.com/issues/2005-10/rhf/index.php

Daily or continuous water change is just about as effective as larger less frequent water changes, given the same total volume changed.

snapshot of one of many diagrams.

first off - i didn't read the article (sorry) but... i will say yes and no... let's say you have a 300 gallon tank with 200ppm nitrates, if you change the entire 300 gallons with perfect water, your nitrates are now 0. if you change 30 gallons (10%) 10 times (300 gallons) your nitrates would be 36ppm (not 0).

this is in a pretend world, because i am not accounting for the fact the DOS may actually replace your now diluted
SW water with SW new water (ie replacing itself) or that you may increase or reduce nitrates in the meantime with fish food/poop or advanced filtration.

larger water changes will always result in more change. smaller water changes result in less risk of shock.

 

[Reefmonsters]

That article is a good read, now only if I could understand it all!!! I have about 130-140 gallon total water volume so my plan is to change about 1.5 gallons per day. I just finished cycling and have 3 small Bangaiis and 1 very small Coral Beauty in now. Looking very forward to Automation and Stability with this build.

 

[arking_mark]

In my opinion, incremental water changes are better. Individually, you are correct, their total removal/replacement of tank water is less (but not that significantly). However, the most important aspect of a successful tank is stability which is where ncremental water changes shine. Also, remember that your tank water has important nutrients that the steril new water doesn't, so doing incremental water changes removes a little less of these as well.

 

[Waters]

I read an article somewhere (maybe from BRS?) that showed that, due to total water volume, there is very little (if any) water being pulled out that was just added. I wish I could remember where I read it at. You will notice more of an immediate impact on coral after a single large water change because you are removing (and adding) large amounts of "stuff" at one time. Would you rather have your coral looking good all the time, or just immediately after a large water change?

 

[xiaoxiy]

Everything that has been posted above is great info!

Another thing you can do to minimize immediately pulling out new water you just added is to pull waste water from upstream of where you add new water. In other words, pull dirty water from the first chamber of your sump/filter and add new water to your return section.

 

[arking_mark]

Everything that has been posted above is great info!

Another thing you can do to minimize immediately pulling out new water you just added is to pull waste water from upstream of where you add new water. In other words, pull dirty water from the first chamber of your sump/filter and add new water to your return section.

Or even remove water 1st and add water 2nd. Again...minimal impact...

 

[xiaoxiy]

Or even remove water 1st and add water 2nd. Again...minimal impact...

Harder to do with the DOS.

 

[arking_mark]

Harder to do with the DOS.

I use GHL Maxi Doser and can do them sequentially...but don't.

 

[Waters]

I am not sure how that would work with equipment (such as skimmers that rely on steady water levels) running during the water change? The DOS could do it......but you would have to shut stuff down until the water change was completed. Mine runs in the background 5 days a week. Maybe I am missing something?

 

[biecacka]

I use the DOS for AWC too. I pull tank water from the drain section of my sump and replace it above my return pump. In my mind it helps me believe that I’m not pulling out any water I just put in. It works for me. That’s what I care about. But, I’m also not fighting high p04or n03. I’m just maintaining levels.


corey

 

[arking_mark]

I am not sure how that would work with equipment (such as skimmers that rely on steady water levels) running during the water change? The DOS could do it......but you would have to shut stuff down until the water change was completed. Mine runs in the background 5 days a week. Maybe I am missing something?

I do small incremental AWC so if I did it sequentially (which I don't), it not enough to impact my sump which maintains a constant water height. A large sequential AWC could drain my pump compartment...

 

[Waters]

I do small incremental AWC so if I did it sequentially (which I don't), it not enough to impact my sump which maintains a constant water height. A large sequential AWC could drain my pump compartment...

I do roughly 3 gallons a day in a 125 gallon system which I consider small but I would think even a gallon a day would be enough to kick on my ATO and dump a bunch of fresh water into the sump. Oh well.....like you, I do the changes at the same time anyways....I was just curious.

 

[Randy Holmes-Farley Verified Community Expert]

Harder to do with the DOS.

But pulling the old water out upstream in the sump accomplishes even better than the theoretical continuous change data shown in my article. I did that.

In general, unless the goal is a big emergency water change, continuous water changes are not enough different than 5 or 10 or 20% changes to make any important difference, and are far, far less human work and no need to adjust anything in the new water, even temperature and salinity.

 

[arking_mark]

I do roughly 3 gallons a day in a 125 gallon system which I consider small but I would think even a gallon a day would be enough to kick on my ATO and dump a bunch of fresh water into the sump. Oh well.....like you, I do the changes at the same time anyways....I was just curious.

My ATO is tied in to the AWC and wouldn't kick in. I've automated pretty much everything with GHL.

 

[Waters]

My ATO is tied in to the AWC and wouldn't kick in. I've automated pretty much everything with GHL.

Ahhh, ok. Nice