Water changes

M

mikedickbek

AC Members
Oct 9, 2007
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Honolulu, Hawaii
Hi, I've been reading through a lot of threads here and have tried to do searches, but for some reason my computer won't open the search results page.
I've found so far that it's about the standard to do a 50% water change once a week after my tank gets established. I'm wondering why this is required. If you have enough filtration, why do you need to change anything? I've got a buddy who has a huge salt water tank and he rarely, rarely has to do water changes.


I know it's a pretty rookie question to ask, but I AM a newbie afterall, so I guess I'm allowed to ask stupid questions.

Thanks a lot,
mike
 
The dynamics of a saltwater tank are not the same as in a freshwater tank but water changes in saltwater help also.

In a freshwater tank, the nitrogen cycle results in the production of nitrates. These can accumulate until they get high enough in concentration to be harmful. In a saltwater tank with live rock and a deep sand bed the bacteria deep in the LR/DSB break down the nitrates to release notrogen gas. This does not happen in a freshwater tank so the only sure way to reduce nitrate concentrations in water changing.

Contrary to common misconceptions, filter units do not remove pollutants from the tank. They merely store them in a place for us top remove. The constant water flow through the filter media traps solids but dissolved pollutants stay in the water column.

Since saltwater tanks operate differently you will seldom see filter media in long term use in those tanks. They, the filter media, are considered nitrate factories in such tanks.

If you want to compare the differences look at the posts on cycling a freshwater tank and then on saltwater tanks. Quite different.

Hope this helps alleviate the confusion. BTW, your friend should consider a regular cycle of water changes. His livestock will really appreciate it. After all, they live in their own toilet.

Charlie
 
:iagree:

Nice post Charlie

Also, just to add to the above, we test for nitrAtes, but in reality its not just nitrAtes that are the culprit.

We use this cheap and easy method of testing the water, and perform maintenance accordingly, which in turn indirectly has the added benefit of removing other toxins and compounds present that can be harmful to our aquatics, but are simply too complex/expensive to test for regularly.

Lastly, only through Water Changes or from a biotic process (plants) can nitrAtes be removed from an enclosed system (ie. Aquarium).
 
there are many things in the water that are helpful to plants. so there is a reason right there. another thing like Charlie Greiner said only way to remove waste is to wc. take the dirty water out and replace it with clean water.

50% water change is common it planted tanks because of the EI method. its adding plenty of ferts for the tank and then cleaning out extra with a major wc.
 
FYI,
in marine tanks , depending on the set up, many use live rock and or deep sand beds. live rock and deep sand beds harbor anaerobic bacteria that utlize nitrates. thus they are more efficient at com[leteing the nitrogen cycle. Marine tanks also utilize 'cleanup' crews, crabs, snails etc that help keep the live sand healthy.
in those tanks it is still best to do water changes but the water changes are much smaller..more commonly 10%.
I do 10-15% weekly in my marine tanks.

but 2 40% in all my Fw tanks.
 
i was under the impression that in freshwater tanks you should only do like a 30-35% change weekly, why would u do 50% everyweek? in a 100 gal tank that would get quite cumbersome no?
 
boostnbuds said:
i was under the impression that in freshwater tanks you should only do like a 30-35% change weekly, why would u do 50% everyweek? in a 100 gal tank that would get quite cumbersome no?
Click to expand...
There are a lot of factors that people use to determine WCs. Probably the single greatest measure would be to simply tets your nitrAtes. If they they climb to 20 (or more) in 5-7 days, you need to change 50-60% of the water so that in the next 5-7 days it will be 20ppm and so on.

Some people try to judge bio-loads and feedings to determine this, and some people do 100% every 3-4 days with breeding certain fish or raising certain frys, but in the end testing your nitrAtes is the simplest and easiest method.

For me, in order to maintain 20ppm nitrAtes in my tanks, my 90G needs 50%, my 30G needs 40% and my 10G needs more like 60%. This is just a product of my filtration, feedings, stocking levels, plants, etc., etc... They DO creap up though, so once a month I do a 75-80% in each tank with my bigger maintenance routines (cleaning sponges, media, glass, etc.)
 
Awesome. Thanks a lot guys. And, in regard to my friends SW tank, I was misinformed, he does do small changes, but he also has lots of live rock and little cleaning critters.
thanks again for clearing this up.
mike
 
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