50% water change? 75 Gallon Tank

Discussion in 'Water Changes' started by beginner, Dec 23, 2012.

  1. beginner

    beginnerValued MemberMember

    i'm just wondering if anyone thinks a 50% water change is too extreme. i'm changing 30% twice a week already. I just think that big of a change with mess with the cycle. my nitrates are 40 after a 30% pwc
    Last edited: Dec 23, 2012
  2. Gordinian

    GordinianWell Known MemberMember

    Welcome to fishlore!

    Personally, I don't think 50% is too much, as long as it's only once a week. I change 50% weekly on my smaller 5 & 10 gallon tanks, and my cycle isn't affected. Just make sure that you leave the filter media alone.
  3. OP

    beginnerValued MemberMember

    thanks for the reply. its just seems kinda odd to see the tank half empty but, changing that much water I never need to worry about water quality issues, ie, PH drift
  4. Meeps83

    Meeps83Well Known MemberMember

    It doesn't mess with the cycle. The bacteria aren't in the water, but in the media in your filter. As long as your water is treated it won't effect your cycle.
  5. AlyeskaGirl

    AlyeskaGirlFishlore VIPMember

    I change 50% or more weekly on both my tanks.

    You can change as much water as you want and won't affect anything. Bacteria is not free floating.
  6. JessiNoel21

    JessiNoel21Well Known MemberMember

    I do 90% changes every week on my Discus grow out tank and on my 280 I do 70% to make sure my water is pristine.
  7. Aquarist

    AquaristFishlore LegendMember

    Good morning,

    50% water changes should be fine for your tank. For my 33g long, I remove most all of the water only leaving enough water in the tank for my fish to swim upright.

  8. shellieca

    shelliecaValued MemberMember

    50% is fine, I do that weekly on all 5 of my tanks. When I was fish IN cycling I had to 2 in one day with no adverse effects. To get your nitrates down I'd do 2 in one day, maybe a 50%, wait an hour or so, retest & do another 30-50% if nitrates are still high.
  9. LyndaB

    LyndaBFishlore LegendMember

    We change out 50% weekly on all of our tanks. If your nitrates are 40, then you have no choice but to do big water changes and also, find out why they're so high.
  10. OP

    beginnerValued MemberMember

    I think the nitrates are high because of the bio load, being 18, 4 inch mbuna's. and two large synodontis cats
  11. hobo

    hoboValued MemberMember

    I change at least 75% of the water every week with no problems
  12. Jaysee

    JayseeFishlore LegendMember

    I do 80% changes. As long as the water chemistry of your source water isn't much different than your tank water, you can do 100% changes if you want

    Your water changes have to be large enough to keep up with the nitrate production, otherwise they will slowly climb despite your changes.
  13. OP

    beginnerValued MemberMember

    I changed 50% last night and it brought the nitrates down to 20:) but really changing that much water all it does is make them spawn.