Please weigh in with your two cents worth : Water changes!

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ambulocetus

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Jul 7, 2004
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Okay, i have heard anything from 25% once a month, 15 % a week, and some who suggest only replacing water lost to evaporation! What to do, what to do!! My tank currently has finished cycling, but is developing a slight film on top (my skimmer hasn't ben bought yet!) - Please feel free to give me suggestions to how much of a water change you do - hopefully if enough people post i will be able to just take an average!!!

Thanks for your help
 
I feel it really depends on the filtration and location of your tank my water stays crystal clear and all perimeters are perfect with a monthly water change of 10%
 
IMO, it really does depend on your tank itself. Tanks with a lot of critters or tanks with a lot of corals etc will use up a lot of the trace elements faster and thus need more water changes. If you have a FO or FOWLR (as I currently have) then you can probably get away with few an small water changes. I'll do 10% once a month (if that). unless you have a heavly stocked tank. If so then you likely will also have higher nitrates and will need to do more frequent/larger water changes to keep the nitrates in check. If you have a lot of corals or inverts then you'll need to either replace the trace elements they use with additives (And thus test for those elements as well) or again, do more frequent/larger water changes. It all depends on your tank. :D
 
The "need" factor is only one aspect. And by that I mean, what do your corals need and what needs to be replaced. The waste export is the 2nd most common reason for water changes, but...think about it. If the cycle is doing its job, your not going to need to export nitrates and nitrites...the cycle will do it. What you will need to export are heavy metals that are deposited into the tank via impure water (top off) and possibly food or additives.

Look at it this way...picture the heavy metals as gravel. Your tank is a 5 gallon bucket. Initially you fill it up..(gravel and water) . Day one...gallon of evap, so a gallon of water/gravel back in. Same on day two. What will eventually happen? The gravel will make the water unihabitable for the fish...right?


As far as what percentage...what is your goal? It should be to keep the tank as stable as possible. This means that the parameters fluctuate as little as possible. Again, that means smaller water changes more often. If you do 5% a week, in the average month, you would have changed 20% of the water! Thats ideal and you didnt have a large impact on the corals and fish!
 
SquishyFish said:
The "need" factor is only one aspect. And by that I mean, what do your corals need and what needs to be replaced. The waste export is the 2nd most common reason for water changes, but...think about it. If the cycle is doing its job, your not going to need to export nitrates and nitrites...the cycle will do it. What you will need to export are heavy metals that are deposited into the tank via impure water (top off) and possibly food or additives.

Look at it this way...picture the heavy metals as gravel. Your tank is a 5 gallon bucket. Initially you fill it up..(gravel and water) . Day one...gallon of evap, so a gallon of water/gravel back in. Same on day two. What will eventually happen? The gravel will make the water unihabitable for the fish...right?


As far as what percentage...what is your goal? It should be to keep the tank as stable as possible. This means that the parameters fluctuate as little as possible. Again, that means smaller water changes more often. If you do 5% a week, in the average month, you would have changed 20% of the water! Thats ideal and you didnt have a large impact on the corals and fish!
I'm not sure how doing water changes would remove heavy metals.. why would heavy metals be floating around in the water column?

And if your goal is to export unwanted buildups then 5% just isn't going to make an impact.. you'd be better off doing the 20% once a month. I'm too lazy to go into the math behind dilutions but I'm sure everyone knows it by now.
 
I rely on water changes to replenish the trace elements that become depleted over time. I do not add any other chemical to my water. I do 10% everyother week (or so). Top off every other day, I go topless and it evaporates pretty fast.
 
I think it is funny that people are so scared to put trace elements into their tank without testing each element. Do you test each element of the Salt water you do changes with -- NO! Also, if stability is a factor in the health of a tank, then water changes are actually a bad thing. I understand that people think water changes will remove wastes and metals and all the other bad stuff, but the truth is that unless you are doing massive water changes, you cannot effect the water chemisty very much. Thnik about it, if you did 50% water changes, and your Nitrates were at 20, then the best you could get would be 10 nitrates, but that is also assuming the nitrates are always equally distributed in the water. (Which they are not!) And as for the trace elements, you would only be putting half of the initial amount back in, so you could actually still be deficient in the available trace elements.

If you cannot tell, I am an advocate of watching your parameters and doing changes when there is a real reason. If my filtration is working right, I do not do anything but top off and add trace elements, but then again I am usually on the minority side of ideologies anyhow.
 
I have found that for me anyway smaller more frequent changes have worked great.I have a 55 gal reef and do a 5 gal change every 10 days or so.
 
Atari,

Re-read it. I said 5% once a week wich will, on average, total 20% monthly.

Heavey metals end up in the water column through a variety of ways. Everything from additives that you may be using, to the salt you use for water changes.

Additives are a big way they end up there. Lets say you use Kent Calcium which is around 95% pure. The other 5% will have a lot of heavy meatals in it.

Heavy metals are unfortunately something that are fact in our tanks, but very few seem to be aware of.
 
SquishyFish, 5% once a week does not equal 20% monthly :wink:

Also I didn't say heavy metals weren't there, I asked why they would be floating around. One of the worries of a dsb is supposed to be the build up of heavy metal deposits ie they sink!
 
Heavy metals will cummulate on the sand bed and LR overtime, they have difficulty staying suspended due to their weight, but this is not what they mean by heavy. And 5% weekly would equal about 16% turnover give or take because of the removal of part of the preceding 5 gallon changes. With that logic, there is still 84% or so of the impurities, and over time the small changes will not keep that constant and it will build up requiring massive changes to take care of the wastes. I still think you have to build up the filtration system on all fronts so that it can be self contained and not require water changes. Adding trace elements is still the easiest way for me to stay in control. JMO! Everybody does it differently and it works manyt different ways.

Not to mention Squishy, I am doing some consulting in Chicago and may be able to hook up with Scuba_Steve to get some sand. If I can get it worked out, I will try and get some back for your, but it may take a few weeks/months to get it all back to Dallas.
 
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