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RO vs Tap

P

Pixies

New Member
Joined
25 Aug 2024
Messages
16
Location
Edinburgh
Hi. A bit of background first:
I started (like many, I guess) as wanting to keep an aquarium for fish. I wasn't particularly interested in plants to start with, although I knew I didn't want plastic decorations. This was 15 years ago. Now over the years the plants have increased.

I always had trouble with algae (mainly green hair). I'm in Edinburgh so the water is very soft, it's also quite high in Phosphate. My son was dabbling in a marine reef tank so was getting RODI water from the local shop. After some very limited reading and advice, I started using RO water myself, with JBL Aquadur - and things improved greatly. For years I carried on like this and after a few tank upgrades I've still been using it. However, at the start of this year the green hair came back with a vengeance and I couldn't get it out of the Java moss and driftwood. I eventually relented and completely stripped out everything and started a fresh tank. I'm wanting to have more plants now and after finally researching online (here mainly) realise that this will be my main defence against algae. Also, I see that phosphate isn't the great evil with a planted tank.

I'm staying lo-tech and the substrate is inert. Perhaps I would have used something else if I had committed to a planted tank before redoing it. It's a Superfish Home 85 litre.

Anyway - to my question, eventually: what water should I use?

My tap water (after 4 hour degassing) is: kH:1, gH:2.5, pH:7, phos:4.8ppm, TDS:40
As an example, my tank water before my weekly 50% water change is: nitrate: 10ppm, kH:5, gH:7, pH:7.5, phos:0.05ppm, TDS:200

Is it worth considering going back to using tap water? It is very soft and lacking in TDS. Perhaps using a mix of my usual RO/Aquadur with some tap? Or perhaps even just using tap with Aquadur (or similar)?

Cheers
 
Interesting. You can see how the plants are taking up the phosphate as your tank water is lower than your tap (assuming measurements are accurate and reliable). Do you fertilise, adding P and K? No need for P.

If I had tap water like yours I’d not bother with RO.
 
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hypnogogia said:
Interesting. You can see how the plants are taking up the phosphate as your tank water is lower that your tap (assuming measurements are accurate and reliable). Do you fertilise, adding P and K? No need for P.

If I had tap water like yours I’d not bother with RO.
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Sorry if I wasn't clear. I'm not using tap water in the tank currently. The pre-water-change figures above are for my usual RO + Aquadur.
 
Are you adding fertiliser? I wonder if it's just your tap is so light on everything, that remineralising is adding some nutrients your plants need so it seems like it's better than tap, where as tap+fertiliser would work the same.
 
Thanks everyone for responding and sorry if I haven't made myself clear.
Also - I didn't want to get too much into fertilization, as this isn't the forum, but all things are related anyway.
tam said:
Are you adding fertiliser? I wonder if it's just your tap is so light on everything, that remineralising is adding some nutrients your plants need so it seems like it's better than tap, where as tap+fertiliser would work the same.
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I am using RO water with Aquadur, which adds just kH and gH - no macros or micros. I have been relying on nitrate from fish waste and using Maidenhead's Microbe-Lift Plants Green Fertiliser which is micro-only, along with their Microbe-Lift Bio CO2 Liquid. This was all based on my false aversion to phosphates.

So - is it worth using my tap water to get the additional phosphate? I'll need to add the kH and gH too, as it's lacking from the tap water.
 
What livestock do you have? Your tap water is good and you won’t need to increase GH or KH unless you have shrimp and/or snails, or livebearers who seem to enjoy harder water as well. If you do end up using your tap water, you just need to fertilise micros and potassium and nitrogen.
 
hypnogogia said:
What livestock do you have? Your tap water is good and you won’t need to increase GH or KH unless you have shrimp and/or snails, or livebearers who seem to enjoy harder water as well. If you do end up using your tap water, you just need to fertilise micros and potassium and nitrogen.
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I do have a couple of nertite snails plus neocardinia and amano shrimp.

Aside from the molluscs/crustaceans, isn't a kH of 1 just a bit too low to stabilize the pH?
 
Your caridinia would be ok in low kh and GH of 4-6, but the nerites need harder alkaline water as their shells will otherwise erode. Aim for something like 8 for your kh and GH.
 
hypnogogia said:
Does Aquadur contain phosphate?
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No, it contains ~ Calcium chloride, calcium sulfate, magnesium chloride, sodium bicarbonate, potassium bicarbonate. In no particular order.
Pixies said:
Aside from the molluscs/crustaceans, isn't a kH of 1 just a bit too low to stabilize the pH?
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The kh and gh you have from the tap is perfect for the fish, and plants.
Far better imo than RO water with an added tds of 200. BTW, ditch the Aquadur, you really don't need it.
Water via the tap, add a bit of magnesium. Job done 😀
 
Hi all,
hypnogogia said:
Does Aquadur contain phosphate?
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John q said:
No, it contains ~ Calcium chloride, calcium sulfate, magnesium chloride, sodium bicarbonate, potassium bicarbonate. In no particular order.
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<"JBL Aquadur"> - <"so all right">, other than the sodium bicarbonate (NaHCO3) and all that <"for a mere"> £83 / kg ...........
Pixies said:
My tap water (after 4 hour degassing) is: kH:1, gH:2.5, pH:7, phos:4.8ppm, TDS:40
As an example, my tank water before my weekly 50% water change is: nitrate: 10ppm, kH:5, gH:7, pH:7.5, phos:0.05ppm, TDS:200
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You just need to add a <"lot less remineraliser">, have a look at @Roland's <"Soft water tank">. Basically you are losing all the <"advantages of RO"> by making the H2O solute rich again with the remineraliser.

Personally I'd just use the tap water, assuming that rainwater isn't an option for you? If <"rainwater is an option"?> It is always actually <"my first choice">.
Pixies said:
I have been relying on nitrate from fish waste and using Maidenhead's Microbe-Lift Plants Green Fertiliser which is micro-only, along with their Microbe-Lift Bio CO2 Liquid. This was all based on my false aversion to phosphates.
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Unfortunately we have <"loads of posts like yours">. I'll be honest my opinion is that the major problem with the aquarium industry is that it is full of companies who sell <"useless products, using misleading advertising">.

I'm guessing that the same shop that sold you the JBL Aquadur sold you these as well?

What none of these people will tell you is that plants need <"all fourteen of the mineral nutrients"> essential for growth, they need them in differing amounts, but they must all be present for plant growth to occur. My suggestion would be to buy a complete all in one fertiliser mix, cheapest option is a horticultural one <"Solufeed 2:1:4 and Solufeed Sodium Free TEC or Solufeed Coir TEC Combination">, but something like TNC Complete would do the same job <"TNC Complete | The Nutrient Company"> (but for a lot more money).

Have a look at the Duckweed Index pages, I'm pointing you towards them, partially because I'm absurdly proud <"What is the “Duckweed Index” all about?"> of it, but also because it breaks down <"what is important and what isn't">.

cheers Darrel
 
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Pixies said:
My tap water (after 4 hour degassing) is: kH:1, gH:2.5, pH:7, phos:4.8ppm, TDS:40
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If those are the parameters you get all year long with very little fluctuations I would go tap! If you're in an area with little to no Mg in the tap water (which is likely) - you need to add that (MgSO4 / Epsom Salt) - like 4-6 mg/l or so.

hypnogogia said:
Won’t he need some kh for the nerites?
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My snails and shrimps are fine at ~0.25 dKH. and a pH around 6.2 - possibly lower from time to time. In general; as long as the water contains a fair amount of Calcium and Magnesium (helps the invertebrates with absorption of Ca and of course plants need Mg) and the invertebrates have access to decent calcium rich food, it wont be an issue. In my shrimp tank I keep my dGH around 4.5 or so as well.

Cheers,
Michael
 
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Whilst not as complete or as rich as some more specialised fertilisers the contents of Microbelift Plants green is more than just micro elements, it does lack Nickel and Phosphate so can’t be classed as a complete fertiliser, it’s more an augment to what would naturally be found in municipal tapwater (this is a broad variable and some water sources are more moderated than others), the absence of Inorganic Phosphate can be negated by performing waterchanges with tap water that contains it, it’s a very lean fertiliser. For novices to planted tanks it is better than no fertiliser for increasing plant health, when it’s not enough folks wind up here which isn’t a bad thing.

The contents are -

N: 0.10% - 1000ppm
K20: 0.10% - 1000ppm
Ca: 0.002% - 20ppm
Mg: 0.002% - 20ppm
S: 0.006% - 60ppm
B: 0.003% - 30ppm
Cl: 0.009% - 90ppm
Co: 0.006% - 60ppm
Cu: 0.001% - 10ppm
Fe: 0.009% - 90ppm
Mn: 0.002% - 20ppm
Mo: 0.007% - 70ppm
Na: 0.013% - 130ppm
Zn: 0.002% - 20ppm

Result of one dose of 5ml/100L will add to the aquarium -

N: 0.05ppm
K20: 0.05ppm
Ca: 0.001ppm
Mg: 0.001ppm
S: 0.003ppm
B: 0.0015ppm
Cl: 0.0045ppm
Co: 0.003ppm
Cu: 0.0005ppm
Fe: 0.0045ppm
Mn: 0.001ppm
Mo: 0.0035ppm
Na: 0.0065ppm
Zn: 0.001ppm

As you can see (providing my math is correct) it’s a very lean dose and it’s recommended to dose 1-2 per week. Because the Iron dosage is relatively low and because there can be problems with it’s availability depending on the pH and binding chelate in use my recommendation is to calculate the total for the week and divide the amount to more frequent dosing, say every other day to alleviate the possibility of it bottoming out. If the tank being dosed is an absolute jungle with greedy plants then this fertiliser at the suggested dosage will likely be nowhere near enough to satisfy the plants needs without bumping into Leibigs Law of Minimum somewhere along the way.

The Bio CO2 is Humic and Fulvic acid derived, so a natural plant available long chain carbon molecule that is safer to dose/overdose than other long chain carbon molecules such as Ethanol or Gluteraldehyde based liquid carbon supplements without having to resort to the next level of adding gaseous CO2 and it’s assosciated risks.

I’m not a fan of Aquadur there’s better and cheaper ways to remineralise water.

🙂
 
dw1305 said:
I'll be honest my opinion is that the major problem with the aquarium industry is that it is full of companies who sell <"useless products, using misleading advertising">.
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I would like to see UKAPS eventually respond to the misleading selling. It's not helped by some of the YouTubers who co-promote this stuff. Every hobby has this side but ours seem to be plagued by 'must have' merchandising based on the sketchiest or bogus science. The idea that this can be the simplest of hobbies though one requiring patience (it's aquatic horticulture) gets diminished
 
Hi all,

I'm very grateful to all your replies. I'm going through them all and feeling a bit:

Indecisive Dave

I've a long day at work today - but I'll respond tonight hopefully. I didn't want people to think I was ignoring their responses.
 
Being from Cambridge with liquid rock, I'd kill for your water out of the tap!
I'd always advocate using tap water (species allowing) as its so much easier than the PITA that is making or buying water, not having it when you need it, forward planning WC BS 🤬
 
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