Water Changes

[ThatGuy]

Just curious how much people do and why.

The reason is I see threads where people do 20% water changes weekly/biweekly and still skim and dose and all that good stuff.
Then I read threads where people don't do any, just top off, and say there is no need because between skimming, gfo, biopellets, and dosing there is no need.
Then there's the people that do minimal water changes, and do the same as above, and thats just to replenish the trace elements.


I know I do 5% water changes weekly and just run a skimmer and gfo. No dosing(as of yet). And that keeps everything on the up and up.

 

[GEEGOBAL]

I have a 90 Gallon Fowlr and do 1 (maybe 2) top offs a week with FW (usually a little over 4 cups). As far as my 20 gallon water change...that is every 2 months. Seems to work for me.

 

[joeb558]

I have a 54. Gallon corner tank. I skim, run gfo and carbon. I do a 15 gallon water change every 2 weeks and have an ato running. I change my filter sock every week and occasionally add A&B. so far this has been working well.

 

[mnat]

It all depends on your system and what you have. With my nanos that were coral heavy I had to be diligent 10% weekly as you have a small system volume and sensitive corals. In my bigger system I am more lax, maybe 20% every 2-3 weeks. I still have the same sensitve corals but my tank is pretty understocked and I have an awesome skimmer. Every system is going to be different.

 

[Sunny]

I was doing 20% every two weeks (100G) on my system.

I plan to do it once a month going forward. I have tested this theory for last 2 months and it looks promising.

I might go to once in two months in next few months. We will see ...

 

[ThatGuy]

Thats kind of my question. If you skim heavy(that strips most nutrients(nitrates) leaving water parameters pretty good) and dose to keep up with cal, mag, alk, and trace elements, and ATO with RODI. Why do waterchanges. It seems pointless to me.

My reason for the water changes is I don't dose and my skimmer is barely enough for what I have, if not even that. But if I bumped everything up to overkill, why would I bother with waterchanges. What would be to overall benifit?

 

[mnat]

We do water changes because we have closed systems. We add nutrients daily through feeding and our fish/inverts pooping. You can remove those nutrients through skimming, chemical filtration, and water changes. Chemical and skimming will get most of it but not all of it, water changes will get it all. There are other trace elements in our salt mixes that are best "dosed" through water changes which is another reason.

Sunny has a very big overall system and very good filtration, so he can get away with a lot more than people with smaller tanks.

 

[Sunny]

We do water changes because we have closed systems. We add nutrients daily through feeding and our fish/inverts pooping. You can remove those nutrients through skimming, chemical filtration, and water changes. Chemical and skimming will get most of it but not all of it, water changes will get it all. There are other trace elements in our salt mixes that are best "dosed" through water changes which is another reason.

Sunny has a very big overall system and very good filtration, so he can get away with a lot more than people with smaller tanks.

++ 1 on what Mike said. In a smaller system WC are must. You need to do that because of a closed loop system.
You do have more room for error with larger water volume. However if you have a problem then it is also much tougher to fix it in a larger water volume.
WC is essentially for removing nutrients.

Now, it will also depend on how much you feed.

I have too many tangs and other fish. When I drop pellets in the tank nothing ever hits the bottom. However there is a lot of poop and I mean a lot.
So I also clean my sand when I do WC.

Sunny

 

[NikkiT]

Maintaining a reef tank without water changes would in my honest opinion be pretty difficult, long term. In addition to the pollution and trace elements that Mike and Sunny spoke of, we also have to worry about what exactly is swimming around in our tanks, what gets absorbed by our rock and sand over time, and what happens when that absorption threshold is reached.
As we do our water changes, we help remove harmful life from the water in our systems and dilute the concentrations of parasites and pathogens. All of us have some form of harmful organisms in our tanks, it is just a question of what and how much. Over time, those animals that we cannot see can infest our tanks to such a level that they become harmful to the tank's inhabitants. Could you run a UV to address this issue? Maybe.

Another reason we do water changes is because not all organic pollution is dissolved and can be removed by a skimmer. Flip over a piece of live rock, or look in a nook without too much flow, and you will see accumulated detritus. Doing a water change allows us to negate the negative effects that would otherwise occur over time by physically stirring up the sand bed and manually removing those solids. Now that detritus breaks down over time, and some of it becomes dissolved organic material removed by a skimmer, and some of it becomes phosphates that are absorbed by our live rock and live sand and eaten by algae.
Over time phosphates are absorbed by live rock and live sand from fish poop and fish food, among other sources. By doing a water change, we make it possible for the rock and sand to relase phosphates absorbed previously into the water, so that we can remove them via a water change. Absent the water changes, eventually, the rock and sand reach a tipping point where they cannot absorb additional phosphates and phosphates spike. This can result in an algae spike, or it can lead to a tank crash. Likewise, there is a saturation point for the volume of beneficial bacteria we can grow in our sand beds and in our rock. Eventually, if we don't remove the pollution, we reach a point where nitrogen absorption can drop to unsafe levels for our fish and corals.
A FOWLER tank may be able to survive for a time without water changes, but I cannot imagine a reef tank thriving without water changes in the long term. There is just too much chemistry involved.

 

[Zippy69]

+1! Great explanation Nikki.

 

[saltkreep88]

I went close to a year without a water change but my levels were spot on because I was dosing. Then when I moved I changed about 50% of the water a saw growth the next month like I have never seen before. My growth exploded, so this proved to me that I was missing something that dosing alk, calcium, and mag didn't cover.

Joe

 

[govertical19]

+1 sunny, Nick I, and Mike! I also find when you do more frequent WC it is better for not being lazy... I find for myself if I do not do it more frequently that some times I will get lazy with it and push it off even longer eventually. Hope that made sense. I do around 30 gallons every 2 weeks and I probably 300ish gallons total.

 

[lefkonj]

I was doing 35gallons every other week on my 180 and then changed to 25 gallons every week. I find the more frequent changes have resulted in much better growth for my corals. Fish don't seem to care either way. Personally I shut off my return pumps, drain the sump, them clean the sump fill it back up and turn it on. Keeps my display much cleaner and I end up with a well maintained sump. its also great for making me clean pumps, probes and other things.

Having said that I am looking into automating my water changes completely and doing about 3 gallons a day every day.

 

[Sunny]

Nikki explained it very well.

The key to water change is to clean the sand at the same time also. Blow the rocks in DT as well. How often do you do that?
Now, get a maxijet 1200 and have it always handy. Blow the rocks with it (again I have a large tank so maybe you can do it with a nano powerhead in small setups).
After about 30 minutes detritus should settle on the sand. Now when doing WC suck it up. Whatever detritus settles on rocks get it next WC if your powerheads in DT don't blow it off already.

Key is to not do a lot at same time. Do not disturb sand bed too much. You need to find the right pump to blow.

If it helps, I used to use the hose that filled the water back in my tank to blow powered by a mag 18. It was enough to blow the detritus and not disturb the sand ..

What can I say, this hobby is really a full time job! - LOL

Sunny