Is 40% water change per week too much?

[WhiteTang]

Hi!

Im just wondering if a 40% weekly water change is too much?
Should I cut back to maybe 20% /week? What do you guys think?

I read somewhere that a 20% water change is needed when changing the water every month. 10% biweekly and 5% weekly.

I know that a more often water change is better since that will replenish the water column with various needed "ingredients". So Im sticking with my weekly schedule. But how much is too much?
Is there a thing as too much water change?

[MondoBongo]

to a large extent this depends on the specific tank, feeding regimen, inhabitants, etc...

i have a 75g tank with a 25g volume in the sump, so total system volume of 100g. my tank does best with at least a 15g each week. i can do 20 gallons every two weeks, but i tend to grow more algae than i like.

i feed heavy, and if i could, i would redo my rock pile. so those are factors.

so figure out what works for you.

another thing to consider is what your goal is. do you want to reduce nitrate? maintain a certain alk/cal/mag level? etc... if you're not supplementing alk/cal/mag, or don't run a skimmer, or feed heavy, or whatever, larger and more frequent water changes may be better for your system.

although personally 40% by volume per week seems very high. is there a particular reason you settled on that amount?

really any specific numbers people throw out in regards to water changes are just general guidelines. you have to do some experimenting and see what works best for you rig.

[tanksfishtank]

Yeah, I would say 40% is a lot. 20% should be more than enough. If you are having problems that require more than20%, you need to look at other things that may need attention in your system.

[thegrun]

It seems a waste of money to make such large water changes weekly unless there is some underlying reason for larger water changes (high nitrates...). In addition unless you match the water parameters closely it would likely stress the corals and fish. I make 10% water changes on my small tanks (under 50 gallons), 15% bi-weekly on larger tanks.

[ptreef]

Hi!

Im just wondering if a 40% weekly water change is too much?
Should I cut back to maybe 20% /week? What do you guys think?

I read somewhere that a 20% water change is needed when changing the water every month. 10% biweekly and 5% weekly.

I know that a more often water change is better since that will replenish the water column with various needed "ingredients". So Im sticking with my weekly schedule. But how much is too much?
Is there a thing as too much water change?


Waste of money...

10% a month is more than enuf "in general"

WC is more for removing excess nutrients than adding "ingredients". Corals really don't strip ingredients other than CAL ALK & MG.....

Need a few more details on your system like load, and skimmers, dose(?), kalk in top off?? and age etc... for better recommendation.

Also any issues right now like HIGH po4 or nitrate or algae

I go 10% every 3-4 mos on SPS dominate w/o issues. I only change because i vacuum sump really or do some gravel vac and need to replace water.
I dose the cal alk & mg

[philosophile]

How big is your tank? If it's a nano, that's heavily stocked, 40% might be reasonable.... But usually that is a little high. You'd be flushing perfectly good salt (and money) down the drain.

[shesacharmer]

I agree. 40% is a lot...UNLESS...as stated you have a very small tank and no sump or skimmer and you are trying to address a problem. To reduce nitrates that's a good method...but you need to find out why the nitrates are so high and address it. If you are just trying to settle on a maintenance schedule then I wouldn't change so much at once...save your money for a new frag! I have a 75 with a lot of rock and a 30 gallon sump with refugium. I try to change about 14 gallons a week and my tank is staying pretty stable with that. I settled on that number because that is how much one of my salt mixing barrel holds! :-)

[WhiteTang]

Hey guys!
Thanks for all the replies.
This is my first saltwater tank and I've been in the hobby 6 months now. I have a 16g Nuvo tank. No skimmer. I have a built in sump full of matrix (same as live rock rumble). I run som activated carbon and phosguard plus purigen. The display tank has around 6kgr live rock and another 2 kgr live sand. Livestock is: One small clown 3/4 of an inch and a chromis same size. I feed twice a day but not heavy... My corals are 2 acans LPS corals with 5-6 heads each, another small favia coral, a small euphyllia coral and a trachyphylis coral. Invertebrates: 2 sexy shrimp and a cleaner shrimp. My tank has zero nitrates nitrites and ammonia. PH is 8,2, Ca around 450 and magnesium 1500. Alkalinity is low, around 6dKh but I dose carbonates for that to get it around 8dKh.

I've been doing 40% WC cause I thought that was the way to go. Although it feels I replace too much (still good) water.
I think I will start cutting down and do a 15% WC. See how that works out...
Again thanks for the input. I appreciate it.

[Fish Biscuit]

I think you are changing too much water. If you change 2 or 3g once a week that should be fine.

When I had a 12g my tank definitely looked better if I did a water change once a week but it was still ok if I ended up changing out 4g every other week. If you're in the habit of doing a water change once a week stay on that schedule since things can go south fast in such a small tank.