how much is 10%

[baldomero]

how much more or less is 10%of a 90 gallon tank 5 ,10 ,or 15 gallons.

[bkwudzjeep]

9 gallons....so closest to 10.....

May I ask why?

[baldomero]

just curious i do more or less two 5 gallon water changes every 10 days or so.

[Salamander]

I think for most that's on the lesser end of how much people change. Many do upto 20% weekly. Kinda depends on your bioload and efficiency of your skimmer, fuge etc.

[ILoveReefer]

I have a 90g. I do 3-5 gallon buckets a week. It comes out to 13.5 gallons. Like salamader said Bioload, skimmer, fuge, etc all play a big part in how much water to change. I have a fuge and a good skimmer. My bioload is low but I'm into mostly sps corals. I have to keep my water quality high. Is this a reef tank?

[OneDayMatt]

[flamealert]

[uscharalph]

Read the edit above.

[flounderfish]

9 gallons exact

[o0jmadr0x0o]

is the water change suposed to be 10% total water volume or just the display. i have a 75g DT 29g sump 50g fuge so considering almost half of my water volume has no waste producing life in it. how many gallons weekly or bi-weekly should i change?
sorry for the hijack but the thread seemed answered pretty easily

[Racing1]

o0jmadr0x0o - 10% of total volume.... And yes the sump and fuge have waste in them.... You should be doing at least 15 Gallons a week or 30 every 2 weeks minimum....

[Jocephus]

Originally posted by uscharalph
An adult with 6 years of SW experience no less. LOL!!!!

Good job making fun of people in the newbie forum, guys. I'm sure it's appreciated.

[t-bone2]

hmmmm loaded question

[MalHavoc]

keep it friendly, folks.

[chimp]

[Sk8r]

To get 10 percent: Anything up to 100 should be less than 10. To divide by 10, whack a digit off the end with a decimal point. 89 become 8.9. 90 becomes 9.0. 100 becomes 10.0 gallons. 512 gallons becomes 51.2 gallons. To get 50 percent of something, cut it straight in half---or multiply 10 percent x 5. To get 75 percent of something---quick and dirty way is to get 50%, then add half of that again [25%] onto the 50%. Quality check: the sum of your 2 parts has to equal the whole you started with. Ie, 75% of 100 is 50 plus half of 50...75. 25 plus 75 equals 100...so you know you're right.

In reef keeping, you will become expert in certain fractions of your tank and bucket size.

[jimbo78]

Originally posted by Sk8r
To get 10 percent: Anything up to 100 should be less than 10. To divide by 10, whack a digit off the end with a decimal point. 89 become 8.9. 90 becomes 9.0. 100 becomes 10.0 gallons. 512 gallons becomes 51.2 gallons. To get 50 percent of something, cut it straight in half---or multiply 10 percent x 5. To get 75 percent of something---quick and dirty way is to get 50%, then add half of that again [25%] onto the 50%. Quality check: the sum of your 2 parts has to equal the whole you started with. Ie, 75% of 100 is 50 plus half of 50...75. 25 plus 75 equals 100...so you know you're right.

In reef keeping, you will become expert in certain fractions of your tank and bucket size.

so whats 10% of my water volume in a 90g with about 125-130lbs of LR and 160lbs of sand?

[jimbo78]

nevermind, i change 15g every 8-10 days

[Sk8r]

Since the water permeates the sand to about 30%...penetrates your holey rock to about 10% [ballpark] and all that masses about 20%-30% of your tank space...you throw your hands in the air and ballpark it at about 10% less water than you think you have if you're figuring additives...

and if you're figuring medications---you take those lil' fish out to quarantine where you have bare walls and a precise calculation possible, 'cause medications are more dangerous than additives. And you never dose your tank's biosystem, because you'll kill it--for that matter.

Myself, I don't calculate for the live rock and sand on most additives, because that much overdose won't hurt a 54g tank plus 30g sump/fuge, not on alk and cal, mg or even iodine or strontium.

Which is another reason to have a sump: my 54g tank becomes an 84g tank...EXCEPT when I'm calculating whether or not I can have a tang in my tank. The answer is no. For fish, I'm a 54. For additives, I'm an 84.

If I were dosing Flatworm Exit, I'd be about 10% conservative just in case. Some remedies can be darned dangerous.

I do, however, as aforesaid count my sump/fuge as well as my tank. Water in the lines is another 2 gallons...[I have a 2-story setup].

AND---another part of what is actually a sensible question---precise calculation matters more in a 34g tank with no sump than it does in a 134 gallon tank with a 50g sump. In little tanks, a quarter of a teaspoon difference looms much, much larger.

Which is why we say little tanks are skittish critters and do need as careful an approximation as you can get. Do your math on those. Ballparking on the big ones is much safer than on the little ones.

It probably would be a nice thing to know, when you water your new tank for the first time, atop all the rock and sand, exactly how much salt water is in your system. But most new tank owners are too excited to be that measurement-oriented.

[baldomero]

thank you jimbo, if you take the live rock and sand out your tank you end up with less than 90 gallons of water right or wrong.AND AS FOR THOSE TWO CLOWNS IN THIS FORUM MATT AND RALPH I THOUGHT WE WERE HERE TO HELP EACH OTHER IF I WANNA GET CRITICIZED IL ASK MY LFS.THANKS

[jimbo78]

no prob, i wondered the same thing once so i figured that was what you were asking. don't let them bother you

[jimbo78]

like i said before i change about 15g every+/- ten days . with the bioload you have in your tank you might want to do 15g a week

[baldomero]

jimbo you have a reef mine is a fowlr i think 10 gallons a week is good what do you think.i understand about my bioload,but my water parameters are always good never had a problem with nitrite,nitrate,ammonia,or ph

[m2434]

Originally posted by baldomero
IF I WANNA GET CRITICIZED IL ASK MY LFS.THANKS

[ILoveReefer]

Changing 10g every 10 days sounds like it's working good for you. If your water parameters are good then keep doing what your doing.

[baldomero]

thanks reefer finally some good advice.

[tapplehave]

Baldomero, 15 years ago I calculated my live rock water displacement and my sump and I came up with a magic number of gallons to change weekly. My water chemistry was always all over. Now I do a ten gallon water change once every two weeks, adding only Kalkwasser (because I always have) and I don't even check my chemistry. You are doing fine, and your tank probably looks fine.