Dosing for a Barr non-CO2 method tank

[hotweldfire]

Barr/Walstad type nano (first link in my sig) with the aim of no or minimal water changes. Has been running about 4 months. Current stocking is 2 hisonotus leucofrenatus (black otos) and about 50 cherry/sakura shrimp (and some random snails). These get fed a tiny bit twice a week max. No co2 injection (including liquid) and only 11w light. Middling level of planting slowing growing into heavily planted.

Have more than 250ml of TPN+ and 250ml of TPN. Also have ADA green brighty step2 and brighty k. Also have some Aquariumplantfooduk all in one EI mix (used on my main tank).

Have been using TPN+ at 1ml twice a week. Can't help but feel that this is woefully inadequate but that's mainly because I'm used to EI dosing.

I might add 10 chili rasbora which would significantly increase the amount of NP I reckon but then again I might not. Assuming I keep stocking as is what would be an appropriate dosing regimen? If possible I'm keen to use both the TPN and TPN+. I know they're the same except one has NPK.

 

[ceg4048]

It's not clear why you feel there's a need to adjust the dosing. CO2 grows plants and the nutrient levels support the growth. In a non-enriched tank growth rates are 5X-10X lower, so unless you have algae or deficency syndromes there is no need to add more nutrition.

Cheers,

 

[Morgan Freeman]

Read the plants, are they growing healthily?

 

[dw1305]

Hi all,
I'd agree with "look at the plants", all my tanks are low nutrient and I use an extremely ad hoc approach to nutrient addition, I've called it the "Duckweed index", but really it just means that when growth slows and and the new leaves on the floaters are noticeably both smaller and less green, I add some KNO3. If this doesn't have a fairly quick effect I add a "total nutrient mix". At the moment I use a sprinkle of "soluble citrus feed" (that I bought remaindered in "Wilkinsons") but I would recommend to other people they used a proper "all in one mix" (without ammonia) and used dosing spoons etc.

The Limnobium plants in the image show nitrogen deficiency (bottom left, right and centre). The size of the leaf rosette is dependent upon both light and nutrients, the bottom left plant had been grown in relatively low light, but with higher nutrients and then allowed to exhaust the nutrients in solution. The plant at the top right came from the same growing conditions as the centre plant, but had been fed with KNO3 a couple of days before I took the scan.
The top left plant is what I would expect the plants to look like "normally".

I'm also not convinced about the "no water change" regime, I think with extra stocking you would be safer using some water changes. You could either change a known volume of water every week, or you could use the conductivity meter.
I do regular small water changes (they are small tanks, so even changing 20% of water every day is a small volume of water to change), but I also use the conductivity meter to keep the TDS in the 50 - 100ppmTDS (80 - 150 microS) range that I've found suits the fish I keep. It is worth noting that this is using rain-water, if I started with our tap water it would be about 600 microS out of the tap, but nearly all the conductivity from dissolved calcium carbonate, in that case I would need to find an appropriate conductivity range, but this may be in the 750/800 microS range.

cheers Darrel

 

[hotweldfire]

It's not clear why you feel there's a need to adjust the dosing. CO2 grows plants and the nutrient levels support the growth. In a non-enriched tank growth rates are 5X-10X lower, so unless you have algae or deficency syndromes there is no need to add more nutrition.

Cheers,

Fair point. Two reasons really.

1) Insecurity. Should something start going pear shaped in the tank it would be good to know that I have a key parameter under control and can manipulate it appropriately. So if I know I'm dosing at roughly the right level then I can up it or bring it down as appropriate.
2) Stocking. I have increased the stock in the tank from 6 ember tetras to around (now) 60 shrimp and a couple of hisonotus. Whilst all inhabitants are now contributing to keeping the tank clean they do represent a larger waste production profile. Therefore should I not be reducing the ferts to take that into account?

Read the plants, are they growing healthily?

Yes. All but the HC and the "mini" java fern are doing very well. Slow but healthy growth.

Hi all,
I'd agree with "look at the plants", all my tanks are low nutrient and I use an extremely ad hoc approach to nutrient addition, I've called it the "Duckweed index", but really it just means that when growth slows and and the new leaves on the floaters are noticeably both smaller and less green, I add some KNO3. If this doesn't have a fairly quick effect I add a "total nutrient mix". At the moment I use a sprinkle of "soluble citrus feed" (that I bought remaindered in "Wilkinsons") but I would recommend to other people they used a proper "all in one mix" (without ammonia) and used dosing spoons etc.

Funny you should say that Darrel. Have a look at these for me then:

A couple of leaves with holes but not much yellowing. Can post some more photos if helpful.

I'm also not convinced about the "no water change" regime, I think with extra stocking you would be safer using some water changes. You could either change a known volume of water every week, or you could use the conductivity meter.

Tank is actually getting a 10-20% water change a week at the moment but that is purely down to drip acclimatisation to introduce cherries from my main tank that I'm catching and transferring each week. Will probably go down to one change a month after that. TDS is rather alarmingly in the 300s despite the fact there's no leaching rock in the tank. I think the most likely explanation for that is my dosing.

 

[dw1305]

Hi all,

Tank is actually getting a 10-20% water change a week at the moment but that is purely down to drip acclimatisation to introduce cherries from my main tank that I'm catching and transferring each week. Will probably go down to one change a month after that. TDS is rather alarmingly in the 300s despite the fact there's no leaching rock in the tank. I think the most likely explanation for that is my dosing.

I'd like to see the TDS lower but it will depend upon the tap? supply, in London it could be both hard and salty. If you have a good source of water (RO?) I would change enough water to get it down to less than 200ppm TDS immediately after you've fed the plants. I don't think you can add fertiliser to the tank and do totally without water changes and I'm not sure once a month will be enough, the plants won't use the ions you add in exactly the same proportions as you add them, and the TDS will inevitably rise over time. If you want you could use an occasional re-set large water change (again you would need to measure the TDS until it reaches a "trigger" value), but I would prefer a lower volume, more frequent change.

Funny you should say that Darrel. Have a look at these for me then:

The Amazon Frogbit looks fine, the holes don't look like a deficiency symptom and the leaves look quite healthy. This would suggest they are getting enough N & K, and if you are feeding TPN+ they should definitely be getting enough of all the other elements,

cheers Darrel