AWC Question

reeferericb · Dec 10, 2020

I just set up a DOS pump for daily water changes (2.5 gallons per day). It set up the change to take place over 24 hours. Is there an advantage to doing it over such a long stretch instead of programming it to just take a couple hours? I’m thinking about shortening the time it takes to do it, mainly so I don’t hear the pump every few minutes. If there’s an advantage to longer changes I’m all ears.

Brett S · Dec 10, 2020

The DOS is a fairly slow pump, so you’ll probably still need to set it up to run over several hours. Maybe have it run at night while you are asleep.

But I don’t think there’s a significant difference between doing 2.5 gallons over a few hours or over the whole day, unless that 2.5 gallons represents a significant percentage of the total amount of water in the tank. If that is the case, then doing it over a longer time period will minimize any temperature or parameter differences between the new water and the water in your tank. But if you have, say, 200G in your system then 2.5G even all at once will just be a drop in the bucket.

reeferericb · Dec 10, 2020

It’s a 125 gallon tank plus the sump. The DOS says it can do up to 1.3 gallons per hour, so a couple hours should be plenty. Even 2.5 hours would do it.

Brett S · Dec 10, 2020

Yeah, I think that would be fine. Just make sure that the tube that’s adding water to the tank is downstream from the one that’s removing water. You don’t want to be removing the new water that you just added. In my case I have the line that adds water in my return pump chamber and the line that removes water in the first chamber of the sump where the tank drains connect.

Waters · Dec 11, 2020

I have my AWCs with my DOS only take roughly 2-3 hours while I am home strictly so I can keep an eye on it. I still have a fear of one of the heads failing and having water coming out but nothing going in (or vice versa).

Surfpulse · Dec 25, 2020

so i have a dumb question, even tho you have AWC- should you still do a water change per say once a month? Like a big one, depending on your tank size ?

reeferericb · Dec 25, 2020

Surfpulse said:
so i have a dumb question, even tho you have AWC- should you still do a water change per say once a month? Like a big one, depending on your tank size ?

The auto water changes replaces the need for additional water changes in my mind. I’m new to this, so take it for what it’s worth. I think as long as you have creatures stirring up the sand bed there’s no (or little) need to vacuum it.
I did set up my DOS to do a manual change of 30 gallons if I need it. The daily 2.5 gallons is done at night, the 30 gallons is done over 24 hours. I set up the 30 gallon change because of the problem I had setting up the pump. My water is crystal clear now.

sdreef · Dec 25, 2020

Surfpulse said:
so i have a dumb question, even tho you have AWC- should you still do a water change per say once a month? Like a big one, depending on your tank size ?

https://www.reef2reef.com/threads/a...should-i-change-daily-etc.690213/post-7369476

I'm quoting Randy Holmes-Farley from the thread above, "Changing 1% daily for 30 days is exactly equivalent to one 26% change." So, based on the math, there isn't an additional need to perform larger water change in addition to the smaller automatic water change routinely.

I have my DOS in a location where I don't hear it. For that reason, I extended my water changes to be performed over a longer period of time. My reasoning is, that ultimately it just results in even less fluctuation in the water chemistry and puts a little less demand on the motors. I would also add, the effect of this is negligible and in my opinion its ok to perform the water change over a shorter duration of time.