How To Use Sand In A 35 Gallon With A Plenum?

Discussion in 'Freshwater Aquarium Builds' started by Faytaya, Aug 25, 2019.

  1. Faytaya

    FaytayaValued MemberMember

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    Hello again :)
    This thread is part of three different subjects covering the same topic that I am trying to figure out. Any help is appreciated. :)

    I am planning a 35 long and want a heavily planted tank. I plan to use silica sand and laterite pellets from Dupla with a plenum.

    1) what kind of mesh would be good for use with sand? Are there any that are sold or do I need to DIY this?

    2) how often will I need to siphon my tank with a plenum in place on top of an anoxic filter build?

    3) Should I use a canister filter for the anoxic build? Or use the canister alongside a DIY anoxic filter build?
     
  2. Skavatar

    SkavatarWell Known MemberMember

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  3. JayH

    JayHValued MemberMember

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    I'd get some landscape fabric from the hardware store. It will let the water through but keep the sand out of the plenum. It's not expensive. Looks a bit like a loose weave felt.

    You're going to need to describe in more detail what you have in mind for the anoxic filtration. If the substrate is the anoxic portion, then you're still going to need something to deal with the ammonia and nitrite.
     
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    Faytaya

    FaytayaValued MemberMember

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    It's one of the builds I saw on here using a water pump, water bottle, double sponge filter, and ceramic media
     
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    SkavatarWell Known MemberMember

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    the top part of the substrate will have aerobic bacteria, its the bottom part of the substrate that will be anoxic. as the water moves down the thick substrate, the aerobic bacteria at the top will deplete the O2 creating anoxic conditions for the denitrifying bacteria to thrive.
     
  6. JayH

    JayHValued MemberMember

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    Your original question is still rather vague as to your intentions. Are you looking to replace this with a canister? Run the canister alongside this DIY filter? Tie this into the plenum in some way?

    Without knowing the specifics, my gut feel is a passive sand bed with plenum combined with a double sponge filter pushing water through a water bottle filled with ceramic media is probably not going to be enough filtration unless the tank is very lightly stocked. Of course, this depends very much on the size of the sponges. If the sponges are big enough and there's enough water moving through them, then the sponges will provide enough nitrification.

    I've heard the Fluval Biomax is fairly good for a ceramic media, but most of the others aren't porous enough to harbor denitrifying bacteria that will handle nitrates. Something like Eheim Substrat Pro or Biohome Biogravel would be a better choice for inside the bottle. Of course, unless you're using a 2-liter bottle, you probably aren't going to have room for enough media to take care of all the nitrates. It should help though, and combined with the substrate might do the job.

    If you add a canister, I wouldn't mess with the water bottle filter. Put one of the sponges on the canister intake as a pre-filter, add a couple denser foams to the canister to filter out the finer particles, then load the rest of it with bio media like Substrat Pro, Biohome Ultimate, or Seachem Matrix. If the filter is sized properly for the tank this will take care of your filtering needs and the sand bed will still be there as insurance.
     
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    Faytaya

    FaytayaValued MemberMember

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    I was actually going to run all three side by side. I'm trying to see how far I can take pollutant control, an experiment for a type of fish I hope to keep in the future. If it works well, I should have almost no nitrates, have no ammonia, and no nitrites. The goal is to do water changes less often. Not out of laziness, but because the species I want to keep is extremely sensitive to pollutants and water parameter fluctuations.
    Edit: see Axelrodi neon blue rasboras
     
  8. JayH

    JayHValued MemberMember

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    Beautiful fish, but those pH requirements are going to be a challenge. At the pH level they need, total ammonia nitrogen would have to be over 20ppm for it to be harmful to the fish.

    If you're going to get a canister, I wouldn't bother with the sponge filter. Like I said, put a sponge on the canister intake to filter out the heaviest muck. Then layer coarse, medium, and fine foam in the canister. Finally, put in as much media as will fit to harbor the dentrifying bacteria. Biohome Ultimate, Biohome Biogravel, Eheim Substrat Pro, Seachem Matrix... Any of these would be good.

    You could run all three in parallel, but the canister would do everything the sponge filter would. You could also look into hooking the plenum into the canister filter. Here's a video from Dr. Kevin Novak that explains how to get just a tiny amount of flow through the plenum. The idea is to just get enough flow, one to two gallons per day, to allow the bacteria in the substrate to work more efficiently. You might want to check his other videos where he talks about setting up the substrate to properly support the bacteria. They need iron and it's important to add something to provide that.

     
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    Faytaya

    FaytayaValued MemberMember

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    How would you recommend tackling the PH challenge?
     
  10. JayH

    JayHValued MemberMember

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    I'd go with what causes their natural environment to have such a low pH -- peat moss. Driftwood and Indian almond leaves will also work. All three release tannin into the water as they decay and this lowers the pH. Unfortunately, it also turns the water a bit brown. If you don't mind the look, you're all set. If you want crystal clear, colorless water, then you've got another problem. My recommendation would be to convince yourself this is the natural habitat for those fish and brown water is what they like.

    There's no set formula for how much of any of these you'd need. It's all going to depend on your tap water and tank conditions. I'd probably start with some driftwood as decoration and then add small amounts of peat to the filter, testing the water a week or so after each addition to see what it does.

    The Indian almond leaves could substitute for the driftwood, but not everyone likes the look of rotting leaves in the bottom of their tank. It does look natural though.
     
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    Faytaya

    FaytayaValued MemberMember

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    I've been considering blackwater for a long time. The challenge comes from pre-conditioning new water for water changes. How would I maintain stable PH during water changes??
     
  12. JayH

    JayHValued MemberMember

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    I just did a bit of research for another thread and there was a connection to this thread. At pH of 6.0 or lower (don't hold me to the exact starting point), it appears the bacteria that process ammonia stop doing so. One of the articles I found about the blue neon rasboras recommends a pH of no more than 5.0. At that pH ammonia shouldn't be an issue. Maybe you don't need any conventional filtration at all. Just do water changes and move the water about enough to keep it oxygenated.

    I would ask around and see what others who keep these fish do about filtration and maintaining such a low pH.
     
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    Faytaya

    FaytayaValued MemberMember

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    That's the thing. I have yet to meet anyone who has successfully kept these fish. That's mainly the reason I want some hardier species---to see how far I can maintain it first and learn how in a more forgiving environment. That being said, most garden variety fish don't live in a ph of 4-5.5, and it'll be a challenge learning how to do this right.
    Edit; someone recommended straight RO remineralized with discus minerals. I wonder if that might work?
     
  14. JayH

    JayHValued MemberMember

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    RO water has a pH of 7.0. It also has no KH, so that would make lowering the pH a lot easier, though with no KH at all the pH swings could be extreme.

    This is a fringe area that I have no experience with, and I'm afraid I was never very good at chemistry, even when I was studying it. My knowledge of pH, KH and such is cursory at best.

    I think your intention of starting with fish that have somewhat more common water quality requirements is a very good idea. Maybe something that prefers just slightly acidic water, like around pH 6.5. That will give you experience with maintaining a steady acidic environment without the requirements being so extreme.
     
  15. Islandvic

    IslandvicWell Known MemberMember

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    I used bulk sun shade material used to make solar screens for decks, windows, patios etc, on top of UGF plates to keep the sand from getting in there.



    I used the solar screen material because I already had it.

    Otherwise, I would have bought weed barrier fabric like @JayH suggested.
     
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    Faytaya

    FaytayaValued MemberMember

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    Weed barrier fabric it is. Thanks for everyone's help! :)
     
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