Water changes, How often and how much?

H

heller792

New member
Hi guys , while having an airstone debate with my LFS yesterday ( see other thread ), the lady in the shop told me I should be changing 25 percent of my water every week. I would like to know if this is true as this would be equal to 100 percent a month and surly that would mean my aquarium would always be on a cycle. More worrying is could you imagine how much I would have to spend on salt.

Cheers guys.
 
Personally I think 10% per week is fine, or 20% every two weeks. On my tank that's almost 20 gallons per week, or 80 gallons per month and a new bucket of salt every 8 weeks.

You don't lose 100% of your water doing four 25% weekly water changes. You slowly dilute your old water because you are changing a mix of new and old every week.

Week 1: 75% old water
Week 2: 56.25% old water (75% of the above figure)
Week 3: 42.1875% old water
Week 4: 31.64% old water
Someone might want to check my math.

If you want to go that route, it probably won't hurt anything other than your pocketbook.
 
your math is pretty much on. but any who, the tank would not cycle because all of the bacteria that is needed to convert amon and nitrites and trates are in your rocks and sand. changing your water would have no effect on this esp if you run a UV there would be nothing living in the water colume esentially any ways. i personally do a 40g water change on about a 13og system a week. i would say the water change would depend on how many corals you have in your tank that use up the trace elements that you are replacing with the water change. my tank is SPS dominated so it requires alot of Ca, Alk, and mag but it also requires alot of the traces elements as well and since i am not really into wanting to does daily aka Ca reactor and Kalk, i really dont want to does trace elements and have to test them. so instead i just do water changes to do this.
 
I do a 4 gallon water change a week on my 40 gollan system. But it is lightly stocked and I run a refuge. I also and 2 part cal-alk every day and trace elements.
 
I change 60 gallons every two weeks, except last week when I had a disaster. I changed 420 gallons (seven 60 gallon water changes) in 62 hours.
 
I change water every two weeks. Normally 20%. For me that is a LOT of water as I have a total of almost 900 gallons.
 
right now i'm doing weekly water changes to get things in check. .normally i'll do 10% a week, but I'm trying to do 20% a week as it appears to have more of an impact.. When I used to keep smaller systems, doing 20% a week was no big deal, and really helped things hum alot..but not really needed.
 
I think it boils down to how much you're willing to change and your budget for salt. I can't find any evidence that fewer water changes is better, but I do see plenty of references to the need to remove coral toxins, detrimental nutrients, and replace trace elements. I know there are plenty that are happy they can go months without one and that's great in terms of maintenance and cost, but I can't see any other benefit.

I change 20% per week minimum, much more if I have something to correct.
 
On smaller tanks ive done 20% weekly
but now on my 220 gallon i just cant afford that
i need a whole 50g bag of IO to do a water change. the bags are 20 bux near me, ive tried online and got it for cheaper but with the shipping it came out to the same thing.
so im forced to only do 20% monthly

is this bad?
 
I think that's probably enough, just my opinion of course. Salt can be wicked expensive for larger tanks. I'm lucky that petsolutions is located about 60 miles from me, so I can order several buckets and pay only $11 for shipping. I see that you have a lot of soft corals, so depending on your overall load you might want to run a decent amount of carbon and change it fairly often. I read a paper I think from Randy Holmes-Farley discussing how carbon will remove some of the toxins produced by the corals. If you can keep your nitrates and so forth in check through other methods you should be good.
 
i have found that experienced reefers change around 5% every 2 weeks, i change 10% weekly, your lfs advisor clearly has absolutely no idea about reef aquaria, i know randy does 1% daily and i have run polls on water changes where every 2 weeks seems to be best, as i mentioned i change weekly but wonder is this is too much, its all about opinions but 25% weekly seems ridiculous, and remember the water you put in to the tank has to be better than what you take out, so its possible water changes in those amounts (25% weekly) are just pointless as the water you put back in is no better than what you have taken out, testing is the key, if you dose as well then changes probably dont need to be done at those percentages
 
well, if you have the following

95 gallon DT
20 gallon sump
120 lbs LR

what is your actual system volume account for the displacement of water from the LR ?

Factoring in all that, I do 10 gallon water changes bi weekly.
 
I may be a little late to the party with my response on this topic, but I get asked that question often at work. When customers call in and the question of water changes comes up during conversation I am often asked how often and how much should be done.

I think everyone has their own preference, based on what works best for them. For me personally, I always recommend 10 to 15% each week or about 20% bi weekly. My personal preference is the small weekly water change, as I find it keeps the PH and some other measurements nice and stable for me. I always like to keep things as simple as possible, and I find that small water changes will cure most of what has ailed my own aquariums at home in the past.

John
 
Smaller, more frequent water changes is always better for your inhabitants. Less stress.

I know Randy does daily small changes (automated) and this is probably the best plan.

I personally change 20% every 2 weeks. Some change once a month and even some never do water changes.

All depends on the equipment you use to maintain the appropriate levels of water chemistry.

John, I think you are providing your customers with some good advice. :thumbsup:
 
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