# No water change dosing possible?



## AlanRR (28 Feb 2019)

I‘m trying to set up my first planted aquarium (low light, no co2) and am feeling a bit overwhelmed by all the fertiliser advice I am reading. I occasionally go away for 2 to 3 weeks at a time so would like a system that can cope with this sort of neglect. I can use pumps to dispense ferts while away but would like to avoid a dosing regime that requires frequent water changes as that wouldn’t be possible when away.

I came across the following article  http://www.sudeepmandal.com/hobbies/planted-aquarium/low-tech-planted-tank-guide/ which suggests that such a setup is possible. Would the doses mentioned there in section 4.6 seem reasonable I.e. for a 20 gal tank weekly doses of...

1/4 Teaspoon of Seachem Equilibrium (for traces and Calcium + Magnesium). (1.42 ppm Ca, 0.42 ppm Mg, 3.43 ppm K and 0.02 ppm Fe)
1/8 Teaspoon of KNO3 (Potassium Nitrate) (5.27 ppm NO3 and 3.32 ppm K)
1/32 Teaspoon of KH2PO4 (Potassium Mono Phosphate) (1.61 ppm PO4 and 0.66 ppm K)

...or are there better options such as just following the low-light guidance at https://rotalabutterfly.com/nutrient-calculator.php?

Any advice (or links to advice) would be greatly appreciated!

Cheers 

Alan


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## dw1305 (28 Feb 2019)

Hi all, 





AlanRR said:


> I came across the following article  http://www.sudeepmandal.com/hobbies/planted-aquarium/low-tech-planted-tank-guide/ which suggests that such a setup is possible. Would the doses mentioned there in section 4.6 seem reasonable I.e. for a 20 gal tank weekly doses of...


You can do this. I'm often away from the tanks for weeks at a time, and they are fine. 

You may need to add some more <"magnesium"> and <"iron"> if you have hard water. 

I don't actually ever feed the tanks on a regular basis, I use the <"Duckweed Index">. When I've been away I have a bit of a thin of the floating plants, when I come back, and then change a bit more water every day until I get down towards my <"conductivity datum range">.

I think all tanks are <"better with water changes">, and the fluctuating CO2 hypothesis is unproven. If you use tap water you can leave the the water standing and that will degas any extra CO2. I'd follow his *Warning* disclaimer for all low tech. tanks.





> Also make sure that you DO NOT perform any water changes at all! The reason for this is that tap water will have a different amount of dissolved CO2 as compared to what is in your tank. If you perform regular water changes you are effectively causing fluctuations in the CO2 levels in your tank which provides a perfect environment for algae to start thriving in. Only perform top offs for evaporated water. *Warning*: This no water change rule should only be used for tanks with high plant density. If you have a tank which is lightly planted and you don't plan on having more than a few plants in it, then stick to doing at least 25% water changes every week. The no water change rule only works if you have enough plants in your tank so that they alone can help cycle the tank and maintain water quality. The same goes for overstocked tanks. While you might risk a little algae from the water changes, fish health is top priority and the lack of decent plant mass might cause a rise in ammonia/nitrite levels which could hurt your fish.) Perform large (60-70%) water changes after any major rescaping where you pull out plants from the substrate and move things around. This is to remove any toxins/ammonia that you might have released from the substrate with all the uprooting. Also do not perform such types of rescaping/uprooting any more frequently than once every 3-6 months.


cheers Darrel


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## AlanRR (28 Feb 2019)

Brilliant, thanks Darrell. According to Yorkshire Water we have soft water (9.3mg/l calcium) so should be ok on that front.

How does the Duckweed Index work? Is it just a matter of comparing colour to the chart that was in the link you included?

I’ve not kept any sort of plants before (aquatic or otherwise) so forgive any stupid questions.

Cheers

Alan


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## AlanRR (28 Feb 2019)

Ah missed the conductivity Datum link...just reading through it now!


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## AlanRR (28 Feb 2019)

Ok so is the Duckweed Index just making sure the Duckweed looks ok and is growing?  How useful is the conductivity measure I.e. would it be worth buying a meter like  https://www.amazon.co.uk/HM-Digital-EC-3-Conductivity-Testing/dp/B007GP70UU or can I just watch the weed?


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## roadmaster (1 Mar 2019)

Would watch the weed. Surface plants have access to plenty of light and atmospheric CO2 near surface.
If they are wanting from nutrient standpoint,they will be first to let you know.
Is safe to assume then, that plants that are lower in the tank and completely submerged would also struggle depending upon species/growth rates.
Floating watersprite works well also.


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## ian_m (1 Mar 2019)

You can of course, just do a slightly lower light version of a "high tech" dosing, which extends the time between water changes.

My tank is currently 5 weeks since last water change, as been away, BUT I am dosing 1/3 EI levels, and lower lighting strength, only 2 T5 tubes as opposed to 4 tubes with lighting time reduced to 4 hours. I use a PLC controller and just set it to "holiday mode", job done. https://www.ukaps.org/forum/threads/how-to-use-a-plc-to-control-your-fish-tank.42993/

Plants look fine and have taken the opportunity to take over the tank, bursting through the surface in places. Fish all fine, albeit having to negotiate a rather full tank of plants. However there is certainly slight green algae film on the glass and BBA on the plants & fixtures, definitely a sign of poor water. This weekend it will get a proper water change and cleanup.

So yes you can extend water change time to much greater than a week BUT you must lower lighting levels and reduce lighting period and as plants won't require so much nutrient you can reduce fertiliser doses. I just leave my CO2 setting as is (reduced time on of course), so as not to upset my carefully set up bubble rate with the drop checker being green at lights on.

However you need to be very careful as the water in the tank is getting "dirtier" all the time due to all the organic waste from plants (and fish). If the water gets too "dirty", algae will very very quickly move in and ruin all your carefully looked after tank.


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## AlanRR (1 Mar 2019)

Great stuff, thanks all. Nice to have so many options!   I guess it’s time to dive in and see how I get on.


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## tam (1 Mar 2019)

You could look at a soil base and might be able to skip the water column dosing all together. Reducing the light period when you are away would reduce demand too.


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## dw1305 (1 Mar 2019)

Hi all,


AlanRR said:


> How useful is the conductivity measure I.e. would it be worth buying a meter like Amazon product or can I just watch the weed?



I like to have a conductivity meter, but it isn't essential. They are low maintenance bits of kit. A low range meter (0 - 999microS) would be more accurate than the linked one, but the linked one would work, you are only after a "ball park" figure.


AlanRR said:


> How does the Duckweed Index work? Is it just a matter of comparing colour to the chart that was in the link you included?


Pretty much.

You assess the health and growth of a floating plant, and use that as an indication of when to add fertilisers. The floating bit is important because it takes CO2 availability (and normally light) out of the equation. A floating plant has access to 400ppm of CO2 and the most intense light levels.

Originally I used _Lemna minor_ (Common Duckweed) because that was the organism used in <"scientific bioassays of water quality">, and therefore called it the "Duckweed Index". 

I know prefer Amazon Frogbit (_Limnobium laevigatum_), mainly because it will grow across the <"whole range of nutrient and hardness values"> that we are likely to encounter in the tank, and has a nice green leaf. You might also be able to get a credit note for any spare at your LFS, or sell it on ebay etc.

cheers Darrel


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## AlanRR (1 Mar 2019)

tam said:


> You could look at a soil base and might be able to skip the water column dosing all together. Reducing the light period when you are away would reduce demand too.



I have bought some Tropica soil for the tank


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## AlanRR (1 Mar 2019)

dw1305 said:


> I know prefer Amazon Frogbit (_Limnobium laevigatum_)



I‘ll add some to the list and see how I get on


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## AlanRR (1 Mar 2019)

Is there anything else I should be adding to the tank from a dosing viewpoint? I’ve just been reading through the forums and it sounds like it might be an idea to add calcium (possibly as shell grit) to my soft tap water to help with buffering...?


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