Bio availability

[MartinG]

Tom,
On the APD you mentioned bioavailability of nutrients in tap water and the need for macros out of the tap to be inorganic. For the chemically challenged is all NO3 and PO4 out of the tap the same? I.e. inorganic and bio available? If not how do I tell? My water company figures are 45mgl NO3 and 2.5mgl PO4. I have assumed my macros are more than sufficient whilst keeping up the water changes.

If its not inorganic bio available and therefore unavailable to plants, can I assume it is unavailable to algae? I could be mistakenly thinking I am NO3 rich when in fact I could be NO3 poor in terms of NO3 available to power plant growth/limit algae?

The NO3 test kit confirms the 45 mgl figure.

Regards Martin

 

[Tom Barr]

Re: Bio availability

Generally inorganic forms are the most bioavailable forms.
Algae can use organic-linked forms of PO4 and Nitrogen.
Few if any plants can.

Test ktis measure total PO4 and N, seldom inorganic so called SRP or Ortho PO4 or DIN or DOC.

DIN or SRP are what the plants use and tells more about the system than total N or P tell you.

If you flush the system with large frequent water changes and dose inorganic forms, then it's all bioavailable.


Regards,
Tom Barr

 

[fishface]

Re: Bio availability

so then does that mean if my tank has a fairly high bio-load (fish, shrimp and snails) and test kit is reading sufficient no3 and po4 levels (20 and .2 respectively) but i haven't dosed anything chemically(inorganic?), then my plants will not be able to use what the tank inhabitants are supplying and i MUST dose chemically?

 

[chubasco]

Re: Bio availability

so then does that mean if my tank has a fairly high bio-load (fish, shrimp and snails) and test kit is reading sufficient no3 and po4 levels (20 and .2 respectively) but i haven't dosed anything chemically(inorganic?), then my plants will not be able to use what the tank inhabitants are supplying and i MUST dose chemically?

Then it's time to do a water change (at least 50%) and refert with inorganic
NO3 and PO4. Lowering bio-load and the amount your feeding will help as well. See Tom's post above, last sentence.

Bill

 

[fishface]

Re: Bio availability

i do weekly 50% water changes and just from feeding regularly i get all i need, but if it's the wrong kind of nutrients...won't i be overdosing if i keep adding inorganic ferts? if i do a 50% w/c every time i would be doing them every day or 2. so is the answer to lose some fish or just feed them way more sparingly?

ps. thanks for your patience and help

 

[chubasco]

Re: Bio availability

Lose some fish (hopefully to another tank ) which would allow you to feed
more sparingly.

Regards,

Bill

 

[JadeButterfly]

Re: Bio availability

hmmm interesting...how would I test if I have too much of a fish load with regular dosing? and weekly 50% W/C

 

[chubasco]

Re: Bio availability

hmmm interesting...how would I test if I have too much of a fish load with regular dosing? and weekly 50% W/C

Test for nitrates after WC/refert, then 1-2 days after, and see what you get.
If it's high, you might want to rethink your fishload and/or feeding habits.

Bill

 

[JadeButterfly]

Re: Bio availability

how much NO3 does frozen bloodworms/brinshrimp and colorbits have...? those are what I normally feed...just to give me an idea....because I am trying to fit few discus into my tank...

 

[chubasco]

Re: Bio availability

how much NO3 does frozen bloodworms/brinshrimp and colorbits have...? those are what I normally feed...just to give me an idea....because I am trying to fit few discus into my tank...

That's basically what I feed too, along with Daphnia, and yes that will up the
NO3. How robust is your filtration? In a 45g, discus, will eat, grow, excrete, and be a problem, and then you can sell them to the Summer Olympic Games Were you planning on removing your other fish when you add the
discus?

 

[JadeButterfly]

Re: Bio availability

wow you remember my tank size lol.

umm..well I was planning to actually keep the dozen of rummynose I have...I never thought of them as a problem...was actually hoping to maybe add a pair of rams too lol.

 

[chubasco]

Re: Bio availability

wow you remember my tank size lol.

umm..well I was planning to actually keep the dozen of rummynose I have...I never thought of them as a problem...was actually hoping to maybe add a pair of rams too lol.

Then I wouldn't get the discus, then. They look best in a nice big, tall tank,
when they look good at all Some nice blue rams with your tetras would
be a much better, in scale, endeavor. YMMV,

Bill

 

[JadeButterfly]

Re: Bio availability

this thread is kinda trippy...

i recall when I first wanted to get discus in my planted tank, Tom Barr suggest the notion of w/c 50% is not necessary because our plants absorb the NO3...so weekly 50% will be fine...

right now, i feel like my dozen of rummynose is already too much 'fish-load' for the tank...and snails...are they beneficial at all? I've tried my best to just 'let them be' since many claim that snails are beneficial...most of the waste are from the snails too...im thinking of taking out the whole population now (if possible).

 

[Ian H]

Re: Bio availability

Jade, most threads tend to be 'trippy'. This thread started as a query on plants utilisation of nutrients................... Now we're on fish stocking. It happens all the time. You have to bare some responsibility for this.

Any organic in your tank adds to the bio load. If you are doing frequent water changes and clean up the detritus etc.you should be able to keep it stable even with a large fish population. My tank is in theory well overstocked, but I don't have any problems and the fish and plants are happy. In time you will establish the regime that suits you and your tank.

Ian

 

[Tom Barr]

Re: Bio availability

If you are doing 50% WC weekly, and not adding KNO3 and have CO2, ............the test kits are likely incorrect or else you have virtually no plant growth.

One of the two.

You may have only 5ppm of NO3 that's really bioavailable and virtually no PO4.
That's not to say that is bad either...........as long as there is enough.

But do not assume the test kits are correct, assume they aren't.

Especially if common sense tells you otherwise (50% weekly WC's, lots of plants, good growth rates, no algae, moderate fish loads etc).

Even at 2 w/gal, 1 full adult well feed Discus per 10 gal, 50% of the total N will come from the KNO3.

So a 90 gal tank with 180 w of light, CO2 and 9 discus would still only perhaps need 1/2 the rec KNO3 that a tank with no fish might need.

Dosing K2SO4, Traces, CO2 etc should drive any NO3/PO4 levels way down unless it's just pathetically overstocked/overfeed.

You can also tell if the plants do better right after a water change and dosing vs later in the week.

WC's add CO2 also, so you might see the lower CO2 a day or two after till the next water change also.

If you have a non CO2 tank, more floating plants help, reduce the fish load.
That is more a balanced approach with the non CO2 tank, wereas the CO2 enriched tanks will do extremely well with frequent WC's so you can have very high bioloads relative to a non CO2 plant tank.


Regards,
Tom Barr