High TDS killing fish?

[Matti]

I've a 55l planted tank that has been running for around two years. Some algae issues, some learning with fertilisers and lights, but it's slowly starting to look like a real planted jungle scape. All great, but fish are starting to die! I didn't have this problem in the beginning and it's been a mystery why now, when the tank is otherwise balanced and plants growing well? Bought seven Sparkling Gouramis two weeks ago, now five dead. Before that all Raboras died.
I finally bought a TDS-meter and the value is 320! So I think that must be the problem. But why so high readings? My tap water is ideal for fish keeping, TDS 50.
I first thought it must be the Seiryu stones I have. But KH and GH -levels are ok, bit on the harder side but still acceptable.
But then I started thinking. The tank is two years old, with fish and shrimp that I'v been feeding once ore twice a day, and I've never siphoned the substrate! So there must be a ton of food and poop debris in it, releasing what ever nasty stuff to the water column. I do weekly water changes, but they don't seem to help.
I bought a siphon, let's see after couple of weeks if I can get the TDS down.

M

 

[MichaelJ]

I've a 55l planted tank that has been running for around two years. Some algae issues, some learning with fertilisers and lights, but it's slowly starting to look like a real planted jungle scape. All great, but fish are starting to die! I didn't have this problem in the beginning and it's been a mystery why now, when the tank is otherwise balanced and plants growing well? Bought seven Sparkling Gouramis two weeks ago, now five dead. Before that all Raboras died.
I finally bought a TDS-meter and the value is 320! So I think that must be the problem. But why so high readings? My tap water is ideal for fish keeping, TDS 50.
I first thought it must be the Seiryu stones I have. But KH and GH -levels are ok, bit on the harder side but still acceptable.
But then I started thinking. The tank is two years old, with fish and shrimp that I'v been feeding once ore twice a day, and I've never siphoned the substrate! So there must be a ton of food and poop debris in it, releasing what ever nasty stuff to the water column. I do weekly water changes, but they don't seem to help.
I bought a siphon, let's see after couple of weeks if I can get the TDS down.

M

Hello @Matti, Sorry to hear about your loss of livestock 🙁 In no particular order of importance: How much water do you change when doing the weekly? Any recent changes to your tap water? Whats your stocking level? What do you dose for fertilizer and how often? Post a full tank picture so we can see the state of your tank. What do you feed your fish? What temp are you keeping them at? Any recent changes you can think of? How are the fish behaving... both the ones that appear "healthy" right now and the ones that were in distress before dying? The more info you provide the better. A TDS of 320 is mostly not a problem by itself...its all about what makes up the TDS... if your tap is 50 and you measure 320 that might suggest that you have a tremendous build-up of something - which could be toxic or benign.... Impossible to tell for sure, but it sounds like you might have a lot of organic waste buildup (of which some will show up indirectly as TDS), so take care of that and do some frequent water changes to stabilize things without stressing out the livestock with rapid swings in water parameters - say do 30% every two days for a week or so. If you can, test your nitrite, ammonia and pH levels - those are handy readings when your livestock appear to be in distress.

Cheers,
Michael

 

[AlecF]

In a semi-related question, I always wonder about the terms used for detritus. Obviously food waste is problematic. But in some Amazon biotopes people seem to leave leaves to rot and create mulm. In my community tank I add leaves and tend to hoover, but I'm attempting a semi-biotope with lots of leaves and branches. I will do water changes, but is it OK to leave some mulm? I can't add much more to MichaelJ's helpful suggestions, but I do have TDS of 300 sometimes, mostly, I think, from adding plant food, and I've seen that referred to here – that a consequence of dosing is higher TDS. So, as MJ says, it's a question of what the TDS is composed of.

 

[jaypeecee]

Hi @Matti

I don't think you mentioned anything about the filtration system in your tank. Please let us have some details.

JPC

 

[dw1305]

Hi all,

But in some Amazon biotopes people seem to leave leaves to rot and create mulm. In my community tank I add leaves and tend to hoover, but I'm attempting a semi-biotope with lots of leaves and branches. I will do water changes, but is it OK to leave some mulm?

I use the <"Biochemical Oxygen Demand (BOD) concept"> as a mechanism for working out how <"polluting items in the tank are">. If a substance doesn't contain (m)any sugars or proteins (the <"low hanging fruit of microbial nutrition">)? Then it isn't very polluting.

Wood is lignified and the lignin polymer is right on the edge of <"being microbially biodegradable"> (it needs almost exactly as much energy put in to degraded it as you get out), so it has a very low BOD value. That is why you can get wooden structures that are <"thousands of years old">.

With dead leaves the plant has withdrawn the sugars and proteins from leaf (which is why they turn from green to yellow, red and brown) before the leaf is shed, so again their effect on BOD is negligible.

cheers Darrel

 

[Matti]

The tank has being running ok, except for a long time BBA problem which can also be released to high TDS? And now the dead fish!
I have a OaseBiomaster 250, with the Aquario Neoliever Outflow to get a more gentle flow. I clean the prefilter every two weeks. No wood, nor leaves, couple of big Seiryu stones that release calcium (next time no Seiryu stones, affect too much the water hardnes.)
Nitrates ok, PH bit too high due to the stones, CO2 injection.
I use AquaRebel fertilizers, macros and micros separately, 1 pump macros every two days and 1-2 pumps micros daily. Weekly water changes 25-30%.

I do now daily water changes to get TDS around 100, and I'm siphoning the substrate. Let's see what happens...


Matti