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Discussion Starter · #1 ·
So I've been running multiple low tech planted tanks for a while and have recently acquired a 29 gallon tank that I would like to turn into a blackwater tank.

So far though I'm finding that info on running a blackwater tank isn't readily available, and the info that is out there is really disjointed and there aren't any really good guides on what to do, where to get stuff, etc.

The tank is going to be sand substrate with (hopefully) oak leaves littered about on top with lots of locally found driftwood and really nothing else.

So I have a couple of questions. This is not going to be a planted tank, but I'm sure you folks can help me out.

1. I need a nice dark colored (preferably brown) sand substrate. In my other tanks, I've used both pool filter sand and play sand, but the PFS and play sand I've found tend to be fairly bright. They usually start as a pretty bright off white and fade to a still somewhat bright tan over time. I don't mind buying sand at a pet store, but if there's another better source for dark colored sand I'd like to know.

2. I've seen a couple of sources that say I absolutely NEED to use RO water to get the PH low. This is JUST for the fish that would typically inhabit a darkwater habitat right? The PH of my water isn't going to have any effect on the look of the tank or tannin leaching or anything, right?

Also, I can get one of these http://www.coralreefsupply.com/index.php?aquarium=ro_cl RO units for fairly cheap locally (it's on clearance + I would have coupons/discount to get it for about $70). Is that RO unit worth it? Is there any reason I would regret buying that RO unit over some other one if I were to expand the use of the unit later on? (like trying a saltwater tank).

3. People keep talking about using peat in the filter. Will this alone be enough to give me the correct colored water?

4. How do I keep the water darkly colored when doing water changes? Add more peat to the filter?


Those are the main questions I have. If you guys have any other tips for me I would greatly appreciate them!
 

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I would not mess with the pH issue unless you absolutely have to, for example, if you stock some wild discus or similar sensitive fish. Lots of south american fish have adapted to higher pH water. Tannin leaching affects pH, not the other way around as far as I know. Peat colors the water yes, but its effect does fade so you would want to renew the peat. There are also blackwater additive products but I have no experience with them.
 

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I would go with Tom's suggestion on not worry about the PH until you find it needed. The worst you can do is have a bouncing PH. I find PH is not any factor at all in my experience as long as it is stable. African at 6.4 and Central at 7.6 and neither seem to care. For the colored look in the water, I would go opposite of my normal advise on wood.
Get green wood with bark still on and you will have automatic brown water. Go with some larger, bulkier wood rather than thin as it will take much longer to soak out and stay more uniform over time. Even if it is just a chunk stuck back in the corner out of sight, it will help color things. This will also help to drag PH lower slowly and may help there.
Bottom line is that I find PH to be a highly over worked item.
 

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Blackwater biotopes:
Blackwater is from the organic matter leaching into the water. In nature it is from leaves, branches and other things. The actual color can be anywhere from yellow through reds, tans to browns. It is not often literally black.
Fish from these waters are adapted to water with a very low mineral content. If you are planning on keeping wild caught or breeding fish from this habitat then you will need water with almost no minerals. GH and KH under 3 German degrees of hardness.
If you simply want to keep some of the easier fish that have been in captivity for several generations then the GH and KH could be higher, perhaps GH as high as 9 degrees (Research the fish), but if there is any way to get it softer that would be better. I would aim for about 5dGH and 5dKH, if that is possible.

In the aquarium you can replicate this as you are planning with wood and leaves. Peat moss is another material that works well for this. Peat can be used in the filter (I put it in a nylon stocking), used to prep the water ahead of time (I do this, too), or used as a substrate. I tried it as a substrate and found it too light weight, any disturbance in the soil and the peat goes flying. Then it settles all over the plant leaves and other things. Each material will make the water a bit different in color. Some more red, others brown, others yellow. New materials will tint the water quite dark, perhaps too dark at first. I used Oak bark in a few tanks and it looked like red wine! Could not see through the water to the back of the tank. If the material you are using is this intense you can boil it in several changes of water to reduce the amount of tannins.
I would not bother buying 'black water extract' in a bottle. Oak leaves and many other species are lying around in the garden for free!

Substrate: The dark sand idea is pretty good, that look is just right for many of the fish from blackwater habitats, but I would suggest using one of the Oil-Dri sorts of materials. They will remove the KH from the water and allow the organic materials to drop the pH. I like Safe-T-Sorb. The color is not that dark, but it is a blend of soft greys and tans. Looks really natural. With no plants in the tank you would need only a thin layer, perhaps an inch or so. However, if you want a sand-like material you could also look into the Pebble Tek product line. This is a quartz material that is added to swimming pool finishes to make the pools different colors. Be careful, some of that product line has real sea shells added. That would add minerals to your aquarium water. You want one of the pure colored materials, not a blend with sea shells. You could, of course get a mix of colors, if you want. Find a swimming pool contractor to get this material. I have a couple of tanks with a similar product (not available any more) and I find it heavier than sand, so cleaning is really easy: It drops right out of the siphon fast, so the dirt is removed quite easily.

Water prep for water changes:
To maintain the soft, acidic water with the black water look I would prepare the water ahead of time. A blend of tap + RO would be best, if the tap water is harder than about 5dGH or 5dKH (Hatchery raised fish) or 3 degrees (wild caught or breeding).
I put a fountain pump in the garbage can and a knee-hi nylon stocking of peat moss and run that overnight. For a 29 gallon the amount of water you might need would be fine to use a 20 gallon garbage can, and not fill it all the way. 15 gallons of prepared water would give you a 50% water change.

If your tap water is too hard, then get the RO unit. I do not know all the details about the one you linked, but having coupons and such sure helps!
 

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I can't help you out with most of your questions, but for the sand, I might have an answer.

I went looking for a natural colored, inexpensive sand several months back while setting up my 25 gallon. I found Quikrete All Purpose Sand at home depot. Paid like $3.50 a bag. It looks like:

My plants LOVE it, the fish love it, the shrimp love it, it's a nice dark color, with the larger pebbles rising to the top of the sand, smaller granuales down lower, so it looks really natural.

Also, to get darker water, you can also try Indian Almond Leaves. Or you can make your own blackwater extract. Get some leaves, drop them in a pot, simmer. Eventually, the leaves will have released all their tannins, your water will have been reduced, and you should have a nice tea colored liquid yet. Add as required to your tank.
 

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So I've been running multiple low tech planted tanks for a while and have recently acquired a 29 gallon tank that I would like to turn into a blackwater tank.

The tank is going to be sand substrate with (hopefully) oak leaves littered about on top with lots of locally found driftwood and really nothing else.

So I have a couple of questions. This is not going to be a planted tank, but I'm sure you folks can help me out.

1. I need a nice dark colored (preferably brown) sand substrate. In my other tanks, I've used both pool filter sand and play sand, but the PFS and play sand I've found tend to be fairly bright. They usually start as a pretty bright off white and fade to a still somewhat bright tan over time. I don't mind buying sand at a pet store, but if there's another better source for dark colored sand I'd like to know.

2. I've seen a couple of sources that say I absolutely NEED to use RO water to get the PH low.

3. People keep talking about using peat in the filter. Will this alone be enough to give me the correct colored water?

4. How do I keep the water darkly colored when doing water changes? Add more peat to the filter?
Hello fellow north carolinian. Check out my blackwater tank in my signature.

1. I use pool filter sand, it will eventually stain to a tan, but I also like the contrast with the light sand with the dark water. You could go with the all purpose sand that was suggested above or go out to a local sand stream and collect your own sand, I'd suggest rising well.

2. RO is a waste of money unless you have really hard water or really nasty tap water. My tap water is neutral pH and very soft, so pH drops as time goes by and stabilizes in mid 6's. Leaves and driftwood will help drop the pH.

3. I dont use peat, I get my colored water by putting driftwood and leaves in the tank and also boiling leaves to make oak tea. Now is a good time to collect a bunch of brown oak leaves to use to make tannin stained water. Collect a bunch and seal them in a bag for later use. Put some in a pot of water, boil for a while till it turns brown, let it cool, add to a bucket of dechlorinized water and dump it in the tank.

4. see 3
 

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Discussion Starter · #7 ·
Thanks for the answers everyone!

I'll be heading to the lake tomorrow morning to gather a bunch of wood and leaves.
 
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