Automatic Water Changes Vs. Bi-Weekly Water Changes......

DarthSimon · Jan 24, 2018

Randy and Others,

I value your opinions. Was just curious what your thoughts were to the benefits of doing automatic, continuous water changes. I recently installed a new Apex DOS Pump for Automatic Water Changes all day. I dos my tank 6500 ML of fresh salt water, as well as pull out same amount. Do you believe this is better, worse or same for health of the tank? I used to to 20 gallons every 2 weeks. My System has a 60 Gallon Total Water Volume... My 6500ml a day equates to about 50 gallons a month total swap.

What are the pros and cons? If I was doing 20 Gallons every 2 weeks, what volume would you pull via AWC?? Does it equal the same??? Do I need to do more???

I also DOS 2 Part Bionic, as well well as NoPox and Magnesium, all levels seem to be stable..
Thank you in advance,

Steve Simon

Randy Holmes-Farley · Jan 24, 2018

IMO the main benefits of auto water changes are for you (far less work matching water and actually doing them) and less for the tank.

I spent only about 10 minutes to make a months worth of water and did nothing else to do the changes.

Tbyram · Jan 24, 2018

So I’ve been researching the same thing. One thing I found is that the DKH of the freshly mixed saltwater will start to drop over time. So when I would mix a batch of Red Sea coral version the DKH is very high (12ish) but when I would use it a week later it was really low 7-8. If you are doing auto water changes then do you just have to up your dosing to compensate for not having more alk in the fresh salt water? Or am I totally mixed up on that?

DarthSimon · Jan 24, 2018

Randy,
So chemistry wise doing a long drawn out water change over time, compared to a bulk change is equivalent?

if I dos 20 gallons of fresh salt water over 2 weeks, or change 20 gallons in one shot every two weeks my tank would look the same, corals would have same growth rates. Water parameters would be similar??

Your saying at the end of day, it’s just more convenient?
I agree the way I have the change working now, all I do is basically scoop salt.

But I’m curious if anyone truly sees and differences subtle or drastic??? Tank water looks cleaner?? Corals opening up more??? Ect...

Randy Holmes-Farley · Jan 24, 2018

Tbyram said:
So I’ve been researching the same thing. One thing I found is that the DKH of the freshly mixed saltwater will start to drop over time. So when I would mix a batch of Red Sea coral version the DKH is very high (12ish) but when I would use it a week later it was really low 7-8. If you are doing auto water changes then do you just have to up your dosing to compensate for not having more alk in the fresh salt water? Or am I totally mixed up on that?

Mixes that start high in alk may drop some, but since you do not need to heat or stir the new salt water, you can minimize the effect. Or start with a lower alk mix to begin with.

In any case, I think the effect will be quite small. The effect of a 1% water change on the alk is very low.

I never adjusted anything.

Randy Holmes-Farley · Jan 24, 2018

DarthSimon said:
Randy,
So chemistry wise doing a long drawn out water change over time, compared to a bulk change is equivalent?

if I dos 20 gallons of fresh salt water over 2 weeks, or change 20 gallons in one shot every two weeks my tank would look the same, corals would have same growth rates. Water parameters would be similar??

Your saying at the end of day, it’s just more convenient?
I agree the way I have the change working now, all I do is basically scoop salt.

But I’m curious if anyone truly sees and differences subtle or drastic??? Tank water looks cleaner?? Corals opening up more??? Ect...

Changing 30% continuously is about the same efficiency as one 26% out then in water change. It’s actually a mathematical calculation. [emoji3]

DarthSimon · Jan 24, 2018

So I have to do more volume continuously then bulk? So 2x20=40 bi weekly, or 45ish continuous is about equal??

Randy Holmes-Farley · Jan 25, 2018

DarthSimon said:
So I have to do more volume continuously then bulk? So 2x20=40 bi weekly, or 45ish continuous is about equal??

2 x 20 = one 36%. They do not just add, two small does not exactly equal one double size. That's why continuous is a little less effective, because it is lots of little ones.

I show lots of comparisons and graphs here:

Water Changes in Reef Aquaria by Randy Holmes-Farley - Reefkeeping.com
http://reefkeeping.com/issues/2005-10/rhf/index.php

Kamden Uelton · Jan 25, 2018

If I had the space in my house i'd try and let my parents get me the automatic WC, I would set it so it does like a gallon or two a day, and on the weekends it'll take out 10 gallons or 20 gallons in your case.

DarthSimon · Jan 25, 2018

So that being said, I will dos more volume of fresh salt water. I have it set to 50 gallons a month basically...: Thats ten more than I did bi weekly. Should I go up to 60 gallons a month???? It’s a push if an apex button lol

anthonys51 · Jan 25, 2018

What’s the objective of the water change. To me that really dictates how much and how often to do. If the sole propose is to replenish trade elements in a lightly stocked tank than 1 gallon a day or 10 percent a week would be ok. If it’s to help keep nutrients down then more would be better. Keeping a Reef tank is like dieting. There are so Many different ways to lose weight and so many new tricks on how to do it and everyone is an expert

. Same with reefing

DarthSimon · Jan 25, 2018

Great post above, I have a mixed reef so have plenty of corals and fish. Probably will do more water volume with awc....

DarthSimon · Jan 25, 2018

Randy!!!
Amazing article!!!!

Randy Holmes-Farley said:
2 x 20 = one 36%. They do not just add, two small does not exactly equal one double size. That's why continuous is a little less effective, because it is lots of little ones.

I show lots of comparisons and graphs here:

Water Changes in Reef Aquaria by Randy Holmes-Farley - Reefkeeping.com
http://reefkeeping.com/issues/2005-10/rhf/index.php

Randy Holmes-Farley · Jan 25, 2018

Thanks,

Happy Reefing [emoji3]

DarthSimon · Jan 25, 2018

Randy,
Do you currently do AWC??

Randy Holmes-Farley · Jan 26, 2018

DarthSimon said:
Randy,
Do you currently do AWC??

I did it for at least 15 years before I took down that tank system. If I set one back up again, I'd very likely do it again.

PonySeaArt · Jan 27, 2018

I’ve done gallon a day AWC in my 150 g tank for many years and everything flourished. I also set up automatic RO water evaporation replacement. My lights were also on a timer to mimic sunrise and sunset as well as moonlight.

DangerDave · Jan 28, 2018

I wanted to try something different this time around since it was going to be my first reef. I’ve done awc on my current tank since day one. It works great! I don’t have a compelling argument for it, except that the tank is happy. I’ve never had a tank start up so smoothly. (I probably shouldn’t say that out loud [emoji23])

Dave