Blackwater beginner. Water questions

I have a tank I'm really wanting to make I to a true blackwater tank (low ph, botanicals, etc)
It currently has lots of driftwood pieces and Indian almond leaves in it that are making the water a beautiful tea color that my ember tetras love. (They'll eventually be moving to another tank)
But my ph is still sitting around 7.0 and I have my heart set on some type of wild betta or licorice gourami and I've read everywhere that the gourami need a ph closer to 4.0.

I can't install an RO unit as we rent. Is distilled water a safe alternative? If anyone has experience with blackwater tanks and could please advise on things like keeping the ph low and good botanicals, etc, i would appreciate the advice.
I'm in no rush and want to do this right but everytime I think I understand something, i have 1000 more questions.


I should note this is a 20g tank. I'm not sure why the prefix says 10g)

 

First of all: Blackwater: Basics and FAQ - Aquarium Article
(I link my article each time)
And here's one you will find extremely helpful: How would you create soft water/low pH for Licorice Gourami? | Aquarium Water Forum | 518001

I can't install an RO unit as we rent.

Please look into RO units available today, there are many that don't have to be installed permanently so even if you rent you are able to use one. I do that too and my landlord told me I would be allowed to install a fixed one if I wanted, provided it can be removed again.

Is distilled water a safe alternative?

Yes, but it's pricey long term. If you calculate a balance of RO vs. distilled an RO unit usually pays off after 1-3 months depending on the amounts you need and the model you use.
Another alternative is rainwater, unless you live in a region with acidic rain.

Any further questions?

 

Any further questions?

For RO or distilled water, do you have to add anything to it beside a water conditioner to make it safe?
I'm seeing RO units that list they put out water with a ph of 6.5-7 (depending on the unit). Should the leaf litter and driftwood be enough to bring the ph down?

What about substrate? The tank currently has a mix of caribsea sand and uns controsoil. Is that okay or is there a better option? Maybe something that helps the ph also?

 

MacZ knows way more than I do but I've heard botanicals typically don't bring your pH down past .5 so you could probably achieve a pH of 6 with an RO unit and plenty of botanicals, then again that's just speculation

 

For RO or distilled water, do you have to add anything to it beside a water conditioner to make it safe?

As both are almost pure water there is no need for a dechlorinator. You only have to add humic substances in the form of botanicals.

I'm seeing RO units that list they put out water with a ph of 6.5-7 (depending on the unit).

That's normal. After some time it goes down to about 6 as it takes up CO2 from the air.

Should the leaf litter and driftwood be enough to bring the ph down?

In quite big amounts and with patience, yes. Read the article, this is answered there in more detail.

What about substrate? The tank currently has a mix of caribsea sand and uns controsoil. Is that okay or is there a better option? Maybe something that helps the ph also?

Plain fine sand, like pool filter sand. It should be inert with no influence on water parameters or adding nutrients.

@MacZ knows way more than I do but I've heard botanicals typically don't bring your pH down past .5 so you could probably achieve a pH of 6 with an RO unit and plenty of botanicals, then again that's just speculation

0.5 is the most you get out of botanicals and leaf litter when using normal tap. With purified water like RO it's very much possible to go lower. Again, and for you too: Read the article, it's not an FAQ for nothing.

 

I've read it about..5 times, i juststill have questions lol

Is it feasible to age water with botanicals in a bucket to keep a consistent ph or is it better to just pre-treat water with something like ph down? And about pre-treating: that just means to treat the water and test it before adding it for a water change, right?

 

And about pre-treating: that just means to treat the water and test it before adding it for a water change, right?

I'll answer this first as it's quicker: Yes. Any kind of preparation of the water before adding to the tank.

Is it feasible to age water with botanicals in a bucket to keep a consistent ph or is it better to just pre-treat water with something like ph down?

In direct comparison I prefer pretreating with botanicals as I despise products like pH down. They come at the price of raising conductivity, which is actually a much more important parameter in blackwater than pH. Also the acid method still requires significant amounts of humic substances to buffer the pH and is only useful if you really need to have certain low-low numbers.
As I doubt you will get the really extremophile Parosphromenus, if you go for something more common like P. linkei, botanicals and/or peat will be enough to reach a solid 5 to 5.5. With botanicals this might take some (6-8) weeks, with peat a week or two.
If you do the botanicals in bucket method, make sure to aerate properly (airstone, or just a tube is enough), so all processes happen oxygenated and nothing can turn foul.

I myself use homemade brewed extracts of alder cones, catappa leaves and rooibos tea and add the leaves to the tank, while discarding the tea bag and reusing the alder cones at least once befor discarding them as well.

 

I myself use homemade brewed extracts of alder cones, catappa leaves and rooibos tea and add the leaves to the tank, while discarding the tea bag and reusing the alder cones at least once befor discarding them as well.

Ooh so basically you make a pre-made kind of "tea" to add to the tank instead of letting water sit in buckets with leaves? I just worry about keeping the ph stable but that seems far more feasible than having a bunch of 5 gallon buckets full of leaves lol

You boil the leaves/cones/ etc and then put the boiled leaves and cones into the tank along eith some of the tannin water that they made? I've always just thrown out the boiled water. Never thought of letting them cool and using it like that. How do you store yours?

 

I just worry about keeping the ph stable

Let go of this. The pH is buffered by the humic substances in the tea. pH drops don't happen in this kind of setup and also it's not the amplitude it's the time. 2.0 pH points are no problem if they happen over the course of 6-10 hours.

You boil the leaves/cones/ etc and then put the boiled leaves and cones into the tank along eith some of the tannin water that they made?

Only the leaves. Cones have seeds in them and those tend to foul.

I've always just thrown out the boiled water. Never thought of letting them cool and using it like that. How do you store yours?

I make it right before the waterchange. E.g. if I want to do the waterchange at 2pm I make the extract between 8 and 11 am. RO water is much too cold and I use the warm extract to bring it to the right temp. If that isn't enough I use a dedicated electric kettle. I store the RO untreated in containers I have left from still buying distilled water. I had no alternative for a while, but it's perfect for RO storage. You can store RO and distilled water technically indefinitely as long as it's closed off airtight.

 

I make it right before the waterchange. E.g. if I want to do the waterchange at 2pm I make the extract between 8 and 11 am.

And you boil them in the RO/distilled water?

Thanks for all your help. It really has helped a TON

 

I don't boil it. I just pour near-boiling water over it and let it sit. But yes, there is no tap water involved at any point.

 

I don't boil it. I just pour near-boiling water over it and let it sit. But yes, there is no tap water involved at any point.

Do you test ph? If so, how? My master test kit only goes down to 6.8

 

Do you test ph? If so, how? My master test kit only goes down to 6.8

I don't really. Strips end at 6.0. Drip tests would go down to 3, but are unreliable and erratic with a KH below 2°. pH-meters stop working correctly with a conductivity below 100. I could use some salt to raise conductivity in a sample without changing the pH. But as I don't have a target value for the pH I just monitor TDS/EC and once in a while check nitrates as an indicator of general nutrient levels (surprise: It's always close to exactly what I add myself).
Monitoring pH is not really a necessity in this type of setup. I know the buffering capacity of the humic substances keeps everything in save range and otherwise the value is too dependent of other factors to make monitoring meaningful.
As long as I don't see the fish acting up there is no need for testing it.

 

And you boil them in the RO/distilled water?

Thanks for all your help. It really has helped a TON

As I understand it, it doesn't matter so much what kind of water you boil it in -- that part's just to kill pathogens and start breaking down the tougher plant matter so it releases the tannins and whatnot. Any water will do.

I have actually started mixing my >300 ppm tapwater half-and-half with my R/O water because otherwise my tank's pH falls under 5 and has absolutely no carbonate hardness at all; I know many people run blackwater tanks much more acidic than that but I'm brand new at this and probably want to wait a bit before I start playing at the extreme ends of things! (Plus I don't want to make conditions inhospitable for the bacteria that keeps nitrogen in check.) I went to add my first fish and checked the water they came in and figured putting something acclimated to a 7.5 pH into a 5.5 tank might not be great for it.

Even with the mixing, I've had to add alkaline buffer in order to get my tank to hold steady at ~6.8. I like the look of IALs but I have textbooks to buy so I just threw in oak leaf litter from my front yard, and a sand-over-peat substrate. The silver lining in the inadvertently low pH is that I have exactly -0- visible algae.

 

As I understand it, it doesn't matter so much what kind of water you boil it in -- that part's just to kill pathogens and start breaking down the tougher plant matter so it releases the tannins and whatnot. Any water will do.

Unless you want to use the extract of humic substances, then it should be RO, too.

I have actually started mixing my >300 ppm tapwater half-and-half with my R/O water because otherwise my tank's pH falls under 5 and has absolutely no carbonate hardness at all;

Then by definition you're not running blackwater.

I know many people run blackwater tanks much more acidic than that but I'm brand new at this and probably want to wait a bit before I start playing at the extreme ends of things!

Good point, though a bit over-cautious.

(Plus I don't want to make conditions inhospitable for the bacteria that keeps nitrogen in check.)

I run my current tank at 5.0 and had the previous one at almost 4, the nitrogen cycle never stopped or stalled. It's a misconception. The composition of bacteria/archaea species in the filter media will adapt. Takes time, but it works thanks to the biofilms on the leaf litter and botanicals.

I went to add my first fish and checked the water they came in and figured putting something acclimated to a 7.5 pH into a 5.5 tank might not be great for it.

That's what drip acclimation is for. I exchanged two of my Dicrossus for a group of tetras a few weeks ago. My cichlids went into a display tank at the store and have been drip acclimated for at least 3 hours to a pH of 7, while I drip acclimated the tetras at home from 7 to 5 for 2 hours. No losses in any direction. The trick is to slowly acclimate, that's all. Well, and the species should be naturally adapted to softwater. Try adapting a Molly to softwater, it will drop dead quite soon, even if slowly aclimated. Osmotic pressure works in th wrong direction for them.

Even with the mixing, I've had to add alkaline buffer in order to get my tank to hold steady at ~6.8.

6.8-7.2 is neutral. Obviously you had to add buffers to get there. Humic substances buffer between 4 and 6. Blackwater (or softwater in general) works by replacing the KH-buffer-system with the buffer system of humic substances.

As Scott Fellman (Tannin Aquatics) keeps saying: It's a mental shift. And he's right.

I like the look of IALs but I have textbooks to buy so I just threw in oak leaf litter from my front yard, and a sand-over-peat substrate.

Any brown leaf will work. I would just probably not take leaf litter from next to a road, inner city parks or other heavily polluted areas.

The silver lining in the inadvertently low pH is that I have exactly -0- visible algae.

If that's your silver lining the reasoning behind this type of setup has escaped you.

Please don't take that as an offence, I just noticed you are still rooted in concepts and ideas that work in standart planted and community tanks as well as aquascaping. I just wanted to set you straight about some of these in hopes you realize it's not all as you expect.

 

Unless you want to use the extract of humic substances, then it should be RO, too.

Then by definition you're not running blackwater.

Good point, though a bit over-cautious.

I run my current tank at 5.0 and had the previous one at almost 4, the nitrogen cycle never stopped or stalled. It's a misconception. The composition of bacteria/archaea species in the filter media will adapt. Takes time, but it works thanks to the biofilms on the leaf litter and botanicals.

That's what drip acclimation is for. I exchanged two of my Dicrossus for a group of tetras a few weeks ago. My cichlids went into a display tank at the store and have been drip acclimated for at least 3 hours to a pH of 7, while I drip acclimated the tetras at home from 7 to 5 for 2 hours. No losses in any direction. The trick is to slowly acclimate, that's all. Well, and the species should be naturally adapted to softwater. Try adapting a Molly to softwater, it will drop dead quite soon, even if slowly aclimated. Osmotic pressure works in th wrong direction for them.

6.8-7.2 is neutral. Obviously you had to add buffers to get there. Humic substances buffer between 4 and 6. Blackwater (or softwater in general) works by replacing the KH-buffer-system with the buffer system of humic substances.

As Scott Fellman (Tannin Aquatics) keeps saying: It's a mental shift. And he's right.


Any brown leaf will work. I would just probably not take leaf litter from next to a road, inner city parks or other heavily polluted areas.

If that's your silver lining the reasoning behind this type of setup has escaped you.

Please don't take that as an offence, I just noticed you are still rooted in concepts and ideas that work in standart planted and community tanks as well as aquascaping. I just wanted to set you straight about some of these in hopes you realize it's not all as you expect.

Not offended at all, but rather super appreciative of all of the information, thank you!