Mr. Saltwater Tank TV Friday Am Quick Tip #63: Subtract This, Add That

If you want to be accurate, then you don’t forget about this part of the equation.

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Comments for this article (42)

  • Mark H. says:

    Nice Tebowing and great tip.

  • Mike says:

    Hi Mark,

    Re-arranged your coral placements or is it just the RBTA that has been on the move?

  • Erik says:

    Good tip thanks. Good Tebow. Gotta go with Tebow.

  • Deb says:

    go pats !! From new England

  • Ben VanderNoort says:

    What the HECH Mark…………………..GO TEXANS!!

  • Who says I have to cheer on the home team Ben?! GO BRONCOS!

  • Thierry says:

    Nice advice master 🙂

    When I saw you take some kinda pose I thought you were gonna dance again afterwards .. but no … *SIGH* I am very disappointed :p

  • Lenny says:

    Dont do a Tebow again please

  • Carl says:

    GO CHARGERS! Oh, wait, they’re not ………..oh well, next year. OK then, Go Broncos…sigh
    Thanks for the tip Tim.

  • CD says:

    Nice tip!

  • Dana says:

    Please, no tebowing. I get enough of that elsewhere, plus, he’s not going anywhere this weekend, pats 41 broncos 27

  • Grant says:

    Nice tip…

    and Tebow is the man!

  • Chris says:

    hey, get some shoes hippie!!!!


  • Frankie says:

    Go Bears!!!!! Wait that’s the other Orange and Blue Team… Go Broncos at least I can cheer on this Orange and Blue Team…. BTW… Tim Tebow- As Skip Bayless says all he does is Win , also you New England Fans Tebow killed New England’s Defense that last time they played- they got lucky to pull off the win….

  • Clark says:

    Go Ravens.

  • keith says:

    great idea

  • Doug says:

    Nice tip….. I have a solana and kept track of how much it took when filling it to capacity with the live rock in it, when I first set it up, so I now know how much was displaced. I’m pulling for the Broncos too, although he isn’t Elway, I like his positive attitude.

  • Larry says:

    I have a 46 gallon saltwatertank im using tap water and have been for about 6months i just bought a RODI system and was to change.the water in the tank . i do have live rock 4 fish and a polyp in the tank. Do i change the water in the hole tank or just do a % of water change

  • TJ says:

    Glad you talked about this because this is something I thought about. What about sand, that displaces some water too?

    How do I determine how many gallons get displaced?

  • Alex Taylor says:

    Love the shout out for Tebow Mark! I never really like the Broncos until this year either. Keep making great videos!

  • Paco says:

    @Larry I believe if u start doing weekly water changes soon u will be 100% rodi …

  • VirtualDan says:

    I say you have to go with the home team, Mark! GO TEXANS!!!

  • Thierry says:

    @larry: I would just continu doong my water changes as usual, but wirh rodi water from now on. After a time you ll be all rodi. Changing it all at once isn’t good anyways.

  • Eric says:


  • ocegueda79 says:

    No!!!! Tebow & go Raiders

  • Luke says:

    Your rock may displace more than you think I just set up a 65 with a 40 gal sump. I put 65 pounds of Fiji dry rock in the main tank and probably 10 in the sump. You also need to remember that the sand dose the same thing. I kept track of how much water went in and I only have about 70 gal total. I have about a 5 inch sand bed. Just something to think about. Thanks for the videos they help a lot.

  • Chris says:

    For all the Tebow fans

    Go Pats

    PS – @Frankie – I’m not sure 41 points is lucky 🙂

  • Jeff says:

    I’m from Denver!!! Go BRONCOS!!!!!!! I never knew you were a Broncos fan. Since when?

  • Monique says:

    Mark I love your tank,but there is one thing, GO NEW ENGLAND PATRIOT.
    I love Tom Brady,my kids too, but for different reason.Have a great week end.

  • Vince says:

    YAA GO BRONCOS its tebow time

  • Wes says:

    WHO DAT BABY!!! Although I do like TT–class act kid that the NFL needs A LOT more of.

  • Sam says:

    Yeah, from Denver, GO BRONCOS!!!!!!!!!!!!!!!!

  • Great tip. I forgot to do this and I have a very small tank so the effect is multiplied! Thanks.

  • eli says:

    boooo boooo broncos

  • jeff walder says:


  • Cliff says:

    Is this a tip from Mr Saltwater tank or did I pull up ESPN by mistake, go Brady!!!

  • Jeff…honestly I can’t say I’m a Broncos fan b/c I don’t keep up with them. I keep an eye on them during playoffs and after that awesome pass over the Steelers, I had to put something in about the Teebow bow!

  • Ike says:

    Mark, why would aerating and heating my mixed water before use, go from a 1.026 down to 1. 016 specific gravity?

  • allen says:

    Hello i.m resating my 150g reef aquarium
    i have coral’s that are doing so well but i wood go to the reef stoer’s
    see a fish that i wood love to add for the reef aquarium and they all way’s
    tell me it not reef safe so i woo like to know what fish are reef safe i know all about tang clownfish and damsel’s i’m looking for other fish to add to me reef aquarium

  • captainsmitty says:

    Thank “GOD” no more Tebow! Superbowl will be a rematch of the Harbowl!

  • Byron says:

    Simple math.

  • Simon says:

    Hey guys,
    Hi Mark. Just wondering about something. When doing water changes does the above rule apply? So if Mark has 90 Gallon Display tank does he do 5% of that or total tank and sump volume? I always thought it was just display tank volume.


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