Tank Water Stained Black

[Gio]

Just got back into the fish keeping hobby after many years. Set up a 40g breeder planted tank with black diamond blasting sand, spider wood, and dragon stone. 
 

The tank is currently going through a fishless cycle. Water was clear for the first 2 days but over time the water started to turn a purplish-black color and got darker each day. Doesn’t look like typical tannins from driftwood. I’ve done 2 75% water changes so far but it seems like the water keeps staining. I rinsed my substrate thoroughly and I don’t use carbon in my filter. Not sure what the cause is but I’ve been leaning toward it being the sand. I’m considering emptying the whole tank and changing the substrate to something different like eco complete but I wanna be sure of the cause before I do it. I’ve tried to research this but have come up with nothing. Any help would be appreciated. 
 

the attached photos aren’t my tank since I just changed the water but this is pretty much what the water looks like over time just to give you an idea (Not as dark as the top pic though)

[Atitagain]

Pics of your tank would be much better to get an idea of what the problem is. Maybe take a pic now post it then wait for the dark to come back take another pic?

it could be your substrate, when you rinsed it did the water turn this color? If you rinsed it well till there was no color change I would say this is not the problem. Did you boil the driftwood? Or rinse it off? Some wood can give off very dark tannins and the fact you say it keeps coming back same color I would guess it’s the wood. If it was the gravel I’d think the color would lighten with each water change.

[HH Morant]

You might try a more coarse (larger particles) blasting sand. It is hard to find sometimes. Most sellers have medium and fine.

It seems logical that medium and fine would be dustier than coarse. I am setting up a new aquarium and was able to get some coarse coal slag blasting media (that is what Black Diamond and Black Beauty are) on EBay. I had to pay more for it, but I think I will like it better than the medium grade, which seems very dust-like to me.

This is my opinion before I have actually used the coarse coal slag blasting sand as a substrate, so take  it with a grain of salt.

[lefty o]

i say its the wood. it can take a while, but give it some time and just do things normally. over the course of many water changes, the tank will get less and less color from the wood.

[Gio]

Here are some current photos of the tank after a water change yesterday. 
 

I soaked my driftwood for close to 2 weeks, changing the water every 2-3 days. It released some tannins but it was brown, not this color. When I rinsed the sand the water never turned this color. Just cloudy. It only started a few days after I filled the tank. I’ve just never heard any issues with the black diamond sand turning water this color. Even my filter sponges are stained black 

[mynameisnobody]

I’ve used the black diamond blasting media in the past. Did you rinse it thoroughly before adding it to the aquarium? To me, it looks like the dust from the media. 

[Gio]

I did. Sprint almost an hour rinsing 100lbs of it with a hose and bucket. I know everyone says it takes time. Didn’t think it would need that much. I like the way the sand looks and would hate to tear the tank down and start all over again. I’m just worried the glass will stain too

Not sure if a water purifier/clarifier will help. Was hoping not to add too many chemicals to the tank and ruin the cycle

[mynameisnobody]

@Gio Does your hang on back have filter floss on it? If not, that would clear it up in a couple of days, tops. If it does, I’d change it every 2-3 days before adding any chemicals. 

[Gio]

@Manny that was the first thing I thought of. Even the filter floss stained black. I feel like I may have rinsed too much of the sand at once

Probably will do a few more water changes and see how it goes

[mynameisnobody]

@Gio If the filter floss is stained black, then I’d change it very very often. Water changes will help, but my guess is the blasting sand needs to be rinsed more thoroughly. Whenever I’d clean any substrate, I fill 25%-40% of a 5 gallon bucket with it, and rinse, empty out, rinse, empty out, until the water is crystal clear. Then and only then is it ready for the aquarium. 

[Gio]

Im hoping with more water changes the residue should leech out of the substrate more and the tank clears up

Plants are doing fine and they cycle is moving along so I don’t wanna disturb any of that. Just doesn’t look like I’ll be adding fish anytime soon

[Wingman12r]

This past week I did the blasting sand myself for the first time. I only did enough for a 10g with a 5g bucket. It took a long time to get it clear. You really have to get the fine particles kicked up into the water column.

[Atitagain]

What about adding extra filtration a couple sponge filters an extra HOB with only filter floss pollyfill is cheap. And do some heavy gravel vacs kick the dust up a few times. Sounds like a lot of work but better than removing and re rinsing. 

[Gio]

@Atitagain I currently have a aqua clear 70 with a pre filter sponge as well as coarse and finer sponges in it. I topped it off with some poly floss. I may consider buying a sponge filter as well for the extra filtration and additional water agitation since one side of the tank doesn’t have as much movement. 

don’t really wanna disturb the substrate to much right now so the cycle doesn’t stall/crash

may also purchase seachem clarity to help bind the smaller particles that the filter can’t grab. Hopefully that helps too

[Gio]

Or something cheaper like aqueons water clarifier