need advice/water changes

[M.Carfi]

got a 400 gallon setup for about 2 weeks now, I took half the water from my 135 to fill, the rest was fresh from the tap.
I have:
fx5 uncycled fresh media
amiracle 400 twin tower sump cycled
and an eheim 2229 cycled

The ph sits around 7.5 to 8 consistently.
The water is about 85.F
There are 7, 8-10" fish in residence

When and how often should I change the water, and what % should be changed on a regular basis. Should I be vacuuming the accumulation on the bottom? or can I take the water from the sump to replace. There are 1" round river rocks as a substrate. 3 of the fish frequently feed from the bottom, and a 4th is a pleco.

Reason I'm asking is because the tank is so deep that I have to practically get in it to keep it as clean as my 135. It's a 2 man job now.

 

[justpgraham]

lol said this before! I would just change 25% each week as normal hose in syphon out . if its a major pain vacuming bottom why not disturb bottom as water is syphoning out ? this way most goes out anyway the rest goes in filters that can be changed when clogged . Your stocking levels are low so i think this would be MORE than enough to maintain great quality

 

[pacu mom]

Water changes are usually based on the nitrates. You need a freshwater master test kit such as API's. In a cycled tank, you will have ammonia and nitrite readings of 0 ppm. To keep nitrates low (many fishkeepers try to keep nitrates below 20 ppm) water changes are done. The only way to know the nitrate level is to test the water. How large and how frequently you do water changes will depend on how quickly the nitrates rise in your tank. In heavily stocked tanks, the nitrates will rise faster.

Frequent water testing will tell you how fast the nitrates rise. If nitrates rise at 20 ppm a week, and you did 50% water changes once a week, this will happen:

Week.............Nitrate
1...................20 (at the end of the water change it will be at 10ppm
2...................30
3...................35
So you can see that 50% once a week would not keep nitrates below 20 ppm.

Once you test your water, if your nitrates are sky high, you should do smaller frequent water changes to gradually bring down the nitrates.

If your tank is not cycled, or is in a minicycle and your tests show ammonia or nitrites, this is another time when water changes are indicated. Gross overfeeding, the presence or dead/decaying matter in the tank, or a power outage which kills off the beneficial bacteria in your filter could cause a minicycle where there is an ammonia or nitrite reading.

 

[Pharaoh]

See other thread.