RO vs Tap

[Pixies]

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

 

[hypnogogia]

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.

 

[Pixies]

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.

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.

 

[G H Nelson]

My tap water (after 4 hour degassing) is: kH:1, gH:2.5, pH:7, phos:4.8ppm, TDS:40

 

[hypnogogia]

The pre-water-change figures above are for my usual RO + Aquadur.

Does Aquadur contain phosphate?

Anyway, I’d use the tap water you have.

 

[tam]

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.

 

[Pixies]

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.

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.

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.

 

[hypnogogia]

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.

 

[Pixies]

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.

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?

 

[hypnogogia]

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.

 

[John q]

Does Aquadur contain phosphate?

No, it contains ~ Calcium chloride, calcium sulfate, magnesium chloride, sodium bicarbonate, potassium bicarbonate. In no particular order.

Aside from the molluscs/crustaceans, isn't a kH of 1 just a bit too low to stabilize the pH?

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 😀

 

[hypnogogia]

Water via the tap, add a bit of magnesium. Job done

Won’t he need some kh for the nerites?

 

[John q]

Won’t he need some kh.

I've got 3 year old nerites in 0.5 kh. In harder water they might live to 4 yrs. 1dkh is fine for snails and shrimp.

 

[simon_the_plant_nerd]

To answer the title question: tap.

Fellow Edinburgh resident.

 

[dw1305]

Hi all,

Does Aquadur contain phosphate?

No, it contains ~ Calcium chloride, calcium sulfate, magnesium chloride, sodium bicarbonate, potassium bicarbonate. In no particular order.

<"JBL Aquadur"> - <"so all right">, other than the sodium bicarbonate (NaHCO3) and all that <"for a mere"> £83 / kg ...........

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

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">.

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.

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