Help Water chemistry issues: unknown sources of nitrate and Kh

[Sulla]

So I can't seem to get my nitrates below 20-30ppm - even after a 50% Water change.
Ammonia/nitrite are zero. The tank is about 6-7 months old.

Also my kh is about 8-9 dgh, whereas tap water is 2-3....wheres the rest coming from?

Any help appreciated. Thank you

Tank details below:
Set up - any inputs welcome on the below and ask if I missed something:

• Size: 275L community tank
• Filters: FX6 + SunSun 304B
  • Media (across the two):
    • Seachem Matrix ~5KG
    • Purigen ~ 240grams - I regenerate every couple of months
    • Sponges
• Substrate: Amazonia V2 about 6 months old. Added ADA fertilizer tabs
• Light: Chihiros WRGB Pro2 - 90cm
  • Settings:
    • 70% across the board
    • 7hr photoperiod
• CO2: To get pearling+PH drop I consume 30ml/min (I have a flow meter). Delivery is via Aquamedic Reactor 1000. Comes on 2hr before lights and off 1 hour prior to lights off - so about 8 hrs/day
• Ferts - NilocG dry homemade mix
  • Macro weekly doses delivered in daily doses prior to photoperiod - I modified the KNO3 a bit to reduce nitrates in general
    • NO₃: ≈ 9.8 ppm (KNO3)
    • PO₄: ≈ 5.2 ppm (KH2PO4)
    • K: ≈ 18 ppm (K2SO4 + above)
    • Mg: ≈ 5.2 ppm (MGSO4)
  • Micro weekly doses delivered in daily doses after to photoperiod:
    • Fe: ~0.90 ppm/week (I add Iron Gluconate as well, the micro NilocG mix is about 0.65ppm/week)
    • Mn: ~0.18 ppm/week
    • Zn: ~0.05 ppm/week
    • Cu: ~0.005 ppm/week
    • B: ~0.05 ppm/week
    • Mo: ~0.003 ppm/week
• Params:
  • Ammonia/Nitrite = 0
  • Nitrate after 1 week of water change ~30ppm
  • GH ~8dG
  • KH~ 9dG
  • PH ~ 7.5 overnight down to 6.5 at photoperiod start due to CO2
• Maintenance schedule:
  • 30%-40% water change weekly
  • Filters clean 1x every approx 2 months
• Livestock:
  • 50-60 community nano fish (guppy, tetras, rasbora, cherry barb etc)
  • 5 otos
  • Gazzilion cherry shrimp - no idea they breed like rabbits
  • 5 amano
  • 4 khuli loaches
  • 5 nerite snails
  • 1 hillstream loach
• Feeding: once every 2 days or so. Combo of live bbs, algae wafers and shikari pellets. V little if any left over after a couple of min.
• Plants:
  • Carpet: Eliocaris Pusilla mini
  • Anubias bareri var. nana (anaubias x. 'Frazeri')
  • Cytpocoryne Spiralis "Tiger"
  • Java Fern (microsourm pteropus)
  • Narrow Leaf Ludwig (Ludwigia Palustris)
  • Rotala Indica "green"
  • Rotala Rotundifolia Blood Red
  • Weeping Moss (vesicular ferriei)
  • PLUS: a random house plant with roots in the water - its not big but I like it (recently added, not in photo)

 

[Naturescapes_Rocco]

Is that seiryu stone? Or similar?
Seiryu stone is a limestone rock. It literally dissolves into your water over time, raising KH. It's a beautiful stone but I refuse to use it.

If it's not seiryu, that doesn't mean it doesn't raise your KH. If you put some strong acid on the rock and it fizzes, it's releasing KH into your water.

Aquasoil might be providing plenty NO3 already, and you're dosing NO3 too. Remember that accumulation is different than dosing. 50% WC will help balance things, but if your plants are taking NO3 from the substrate and not from the water column then your NO3 levels won't reduce much.

Finally, that's a LOT of livestock and some decently rich feeding. They are probably producing 10-20ppm NO3 per week alone.

I keep my tanks between 20-35ppm NO3 at all times. It's not a bad macro to have a good ppm of.

 

[Naturescapes_Rocco]

Also, great tank! Beautiful.

 

[BenB]

Nice tank!

 

[Sulla]

Is that seiryu stone? Or similar?
Seiryu stone is a limestone rock. It literally dissolves into your water over time, raising KH. It's a beautiful stone but I refuse to use it.

If it's not seiryu, that doesn't mean it doesn't raise your KH. If you put some strong acid on the rock and it fizzes, it's releasing KH into your water.

Aquasoil might be providing plenty NO3 already, and you're dosing NO3 too. Remember that accumulation is different than dosing. 50% WC will help balance things, but if your plants are taking NO3 from the substrate and not from the water column then your NO3 levels won't reduce much.

Finally, that's a LOT of livestock and some decently rich feeding. They are probably producing 10-20ppm NO3 per week alone.

I keep my tanks between 20-35ppm NO3 at all times. It's not a bad macro to have a good ppm of.

Awesome. Thank you.

For the stone..who knows, it's definitely seriyu style...so that could a thing....

As for the nitrates...yeah it's got good stocking but it's so overfiltered I'm not fussed. And this is after a die off thanks to a co2 valve malfunction (about 6-7 weeks ago)...I had double the fish at one point and the tank didn't skip a beat wrt algae, parameters etc..

So I decided to split my ferts and dose kno3 separately from the rest, and I reduced the dose by half. We'll see how it goes. Prior I dosed all macros together. It will at least allow me to play with the kno3 independently of the rest..

I hear you about the levels..like 20-30 isn't bad. Having said that on water change day (prior to change, so peak level) it's about 40..then it goes back down to 20-30...
As for kh..again it's not a crazy level, but I just found it odd that it's so much higher than my tap. But the stone I guess will do it. I didn't think I had enough but..I guess I do!

 

[Sulla]

Also, great tank! Beautiful.

From you that says a lot. Thank you

 

[Sulla]

Nice tank!

Thank you so much

 

[Sulla]

Is that seiryu stone? Or similar?
Seiryu stone is a limestone rock. It literally dissolves into your water over time, raising KH. It's a beautiful stone but I refuse to use it.

If it's not seiryu, that doesn't mean it doesn't raise your KH. If you put some strong acid on the rock and it fizzes, it's releasing KH into your water.

Aquasoil might be providing plenty NO3 already, and you're dosing NO3 too. Remember that accumulation is different than dosing. 50% WC will help balance things, but if your plants are taking NO3 from the substrate and not from the water column then your NO3 levels won't reduce much.

Finally, that's a LOT of livestock and some decently rich feeding. They are probably producing 10-20ppm NO3 per week alone.

I keep my tanks between 20-35ppm NO3 at all times. It's not a bad macro to have a good ppm of.

Am I richly feeding? I almost never feed daily..maximum once every two days and often 3. When I do I feed generously but apart from algae wafers all the others go in about 5min.

Is that too much?

 

[Koan]

Am I richly feeding

I came across this interesting post not too long ago, talking about how much to feed

Overfeeding within the aquarium – A stomach only the size of their eyes?

You might have heard the statement before, a fishes stomach is only the size of their eye. As a statement it comes from so many sides of truths, half truths and misunderstanding of fish biology. I …

thescientificfishkeeper.co.uk

Mostly in the context of how hard it is to figure out how much to feed catfish and plecos.

As a general rule, you want to see that all of the competing fish are able to get access to enough food. You can watch and see if their bellies are concave or convex over time.

As long as you're not seeing a lot of leftover food and you're changing the water every week to keep bacterial loads down it should not be an issue

 

[Naturescapes_Rocco]

Am I richly feeding? I almost never feed daily..maximum once every two days and often 3. When I do I feed generously but apart from algae wafers all the others go in about 5min.

Is that too much?

No, that sounds perfect!

The fish will simply produce waste. The #1 waste byproduct will end up as NO3.

Even if you stopped feeding, the fish and shrimp and other inhabitants will eat plant matter, algae, microfauna, etc. and produce NO3.

I just wanted to point out that any tank with as vibrant and dense of livestock as you have will produce a good amount of NO3 each week on their own. Feeding them (which is required to, you know, keep them alive!) will increase it, but even without feeding them they will produce NO3, too.

Sounds like you're not over feeding at all, but I just wanted to say that's where your NO3 is coming from.

 

[Sulla]

I came across this interesting post not too long ago, talking about how much to feed

Overfeeding within the aquarium – A stomach only the size of their eyes?

You might have heard the statement before, a fishes stomach is only the size of their eye. As a statement it comes from so many sides of truths, half truths and misunderstanding of fish biology. I …

thescientificfishkeeper.co.uk

Mostly in the context of how hard it is to figure out how much to feed catfish and plecos.

As a general rule, you want to see that all of the competing fish are able to get access to enough food. You can watch and see if their bellies are concave or convex over time.

As long as you're not seeing a lot of leftover food and you're changing the water every week to keep bacterial loads down it should not be an issue

Awesome. Thank you!

 

[Sulla]

No, that sounds perfect!

The fish will simply produce waste. The #1 waste byproduct will end up as NO3.

Even if you stopped feeding, the fish and shrimp and other inhabitants will eat plant matter, algae, microfauna, etc. and produce NO3.

I just wanted to point out that any tank with as vibrant and dense of livestock as you have will produce a good amount of NO3 each week on their own. Feeding them (which is required to, you know, keep them alive!) will increase it, but even without feeding them they will produce NO3, too.

Sounds like you're not over feeding at all, but I just wanted to say that's where your NO3 is coming from.

Phew. Appreciate it. Thank you!