cant keep alk up
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What is wrong with the larger water changes?
+1 ^
You actually leave more nutrient (larger %) after a smaller water change. It's due to the dilution factor. Many smaller fractions vs one larger fraction. Four 10% water changes does not equal 40%. It equals 34.39%.
Here's the math-
100 x 0.9= 90
90 x 0.9= 81
81 x 0.9=72.9
72.9 x 0.9= 65.61%, so
100 - 65.61= 34.39%, an almost 6% difference from one 40% water change.
As for nitrate/phosphorous-
if this has been high for any length of time, and you have any significant substrate/sand/gravel (it goes into the live rock too), then you will have stored a good bit of the nitrate and phosphorous in that substrate. Simply doing water changes will temporarily change the nitrate/phosphorous concentration in the tank water, until the concentration difference between what's in the substrate and tank water equilibrates (equalizes). The nutrients in the substrate will come out/leach into water with a lower concentration of nutrients, but it does so slowly.
Or, in other words the nitrate/phosphorous stored in your gravel/rock will continuously leach back into your tank water after water changes. This is why many hobbyists get so frustrated and don't feel water changes help lower the nutrients. It will, but it will take time. This is sometimes referred to as 'old tank syndrome'. This is most of the reason why you are seeing the nitrate back up after a week, although some additional nitrate/phosphorous is being added continuously as well.
http://www.advancedaquarist.com/2006/5/aafeature2">http://www.advancedaquarist.com/2006/5/aafeature2</a>
When people with older tanks start carbon dosing for instance, they see the effects of this too. They don't see the same results as people with newer systems and come to the (incorrect) conclusion that 'it doesn't work for them'. It will, but will take more time to get all of those stored nutrients back out of the substrates.
So, what to do?
1) be patient and consistent with water changes over a longer period of time (dilute the nutrients). Or,
2) change out your substrate. This can be done a bit at a time, but I prefer to just do it all at once. A system re-boot if you will. Or,
3) adopt a more advanced method for nutrient export, which can include- growing macroalgae, algal turf scrubbers, denitrifying reactors, carbon dosing, etc.
Whatever you choose to do, I suggest that you learn exactly how it works and why. Only then will you be sure of success and recognize when/why things happen.
Hope this helps.
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Umbrellacorp, the arc is a great source of info, and most of the responses you got are good responses, but they take you in different directions. Do what Bill says: and research fully what ever method you choose to reduce nitrates and correct your imbalance before you purchase it. Then you will be able to make an educated descision on your own with out being pulled 5 different ways on here.
I agree with Ripped Tide and Bill especially on the research part of it. I also, agree with the math in Bill's post. For an experienced reefer, I am sure taking a big swing at something is not a big problem. For someone new like me, going all out may mean just that. "All Out". LOL Going in baby steps helps me to see what results my actions give. I get a much better feel for what is going on and how I can impact it.
What it really boils down too is what sounds right to you. Lots of different ways to do things and not many of them are wrong. You just need to be sure you give it time to work.
What it really boils down too is what sounds right to you. Lots of different ways to do things and not many of them are wrong. You just need to be sure you give it time to work.
I am not advocating large water changes for everyone. What I did do was illustrate how larger water chnges are more efficient specifically where large changes are needed.
I personally use smaller water changes, but for a different reason. I just don't belive large one's are necessary in a well maintained system.
Having done water changes ever since I have been in this hobby, I don't think I can recall a time when doing one was not received well by the tanks occupants. I always viewed it much like opening a window in a stuffy room. The only exceptions may be if temperature and/or salinity were much different than the tanks.
I think we can agree that we all need to limit the nutrients that remain in our systems. How we go about that can take many different forms, and may include combinations. eg-
-limit nutrient import (specifically, control feeding and bioload)
-actively export nutrients (skimming, water changes, macroalgae havest, carbon dosing, etc.)
These activities need to be, at least, in balance. Why?
1) Excess nutrient import leads to bad things (nitrate/phosphate build up)
2) Excess nutrient export usually will not, except in extreme cases. Ultralow nutrient systems 'can' apparently stress corals. I have not seen this firsthand.
-JMHO
I personally use smaller water changes, but for a different reason. I just don't belive large one's are necessary in a well maintained system.
Having done water changes ever since I have been in this hobby, I don't think I can recall a time when doing one was not received well by the tanks occupants. I always viewed it much like opening a window in a stuffy room. The only exceptions may be if temperature and/or salinity were much different than the tanks.
I think we can agree that we all need to limit the nutrients that remain in our systems. How we go about that can take many different forms, and may include combinations. eg-
-limit nutrient import (specifically, control feeding and bioload)
-actively export nutrients (skimming, water changes, macroalgae havest, carbon dosing, etc.)
These activities need to be, at least, in balance. Why?
1) Excess nutrient import leads to bad things (nitrate/phosphate build up)
2) Excess nutrient export usually will not, except in extreme cases. Ultralow nutrient systems 'can' apparently stress corals. I have not seen this firsthand.
-JMHO
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Okay gonna do 10-15% WC every other day until nitrates are back to normal. Then 10-15% weekly. Im not dosing anything anymore either. Thank you all for your help, it is greatly appreciated.
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What type of salt are you using?
So I had to open my big mouth. LOL Using API I figure my Calcium reads a bit higher than it really is. My readings have consistantly been Calcium 420 Alk. 7 (125.3). I did a water change on Saturday and they were right there. Since I had some time today and wanted to take a break from working, I ran a test about 1 hour after my blues kicked in. Calcium was 380 and Alk was 7 (125.3). Magnisium was at 1250. About every two weeks I have to dose my Mag with 7 ml of an epsom salt mix to get it back up. Would the low mag levels have caused my low calcium without Alk changing? By the way, PH has been consistant at 8.2 since I got my refugium up and running with a reverse lighting schedule.
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