Ei and water hardness

[PeteA]

Finally got the new tank cycled and my Neon Tetra in. Was wondering if dosing full Ei affects the hardness of the water in the tank and if so how much is it going to change it by? I'm looking at various fish/inverts that prefer soft water so don't want to push the hardness up drastically.

 

[dw1305]

Hi all,
The addition of calcium and magnesium will raise the dGH, although that addition will make little difference to the hardness of our tap water, as it is about 16dGH all ready. With the carbonate hardness dKH and alkalinity, it depends upon the compounds used, hydroxides will raise pH, and carbonates will raise carbonate hardness, but as a general rule sulphates, phosphates, nitrates and chlorides won't raise either. The ions from the EI will raise the conductivity, but in our tap water that is all ready in the 650 - 800 microS range (from the dissolved calcium carbonate).

Personally I wouldn't keep any soft water fish in high conductivity, or strongly carbonate buffered water, but many of the other posters on this forum do, and don't worry about it.

cheers Darrel

 

[PeteA]

Cheers for that Darrel. I'm running a RO setup as when I started out I found that the water out the tap was very high in nitrate - that's before the days when I found out that high nitrate is fine for fish and necessary for plants! The water is currently reading 4 dKH, 9 dGH and 163 TDS with a pH of 6.4 during lights on so it sounds like I'm just going to have to keep an eye on things for a few days and see if anything happens. It's not particularly heavily planted so I think cutting down on the full dose shouldn't pose too much of a problem.

 

[dw1305]

Hi all,

The water is currently reading 4 dKH, 9 dGH and 163 TDS with a pH of 6.4 during lights on

That sounds OK. Personally I'd measure the TDS before and after the 50% water change. If the values keep creeping up you either need to up the proportion of RO you are using, or reduce the dosing.

If you are adding a calcium compound, or a bicarbonate, to raise the dGH/KH of the water you can stop adding them and just cut the RO with 10%~20% tap. The tap water won't supply any magnesium, because both the Cotswold limestones and Chalk are fairly pure calcium carbonate, so you need to keep the magnesium addition the same.

The NO3 content of the water will not be constant through-out the year, it will depend upon the water source and agricultural activity. You usually get a bit of a spike in spring in shallow aquifers, later in deeper ones. Our tap water ("Wessex Water" water, & about 12 miles NW of Devizes), has very little NO3 in it. This must be because it is sourced from a very deep aquifer, where the water is probably "fossil" (arrived in the aquifer before widespread artificial fertiliser use) or may have lost its NO3 during extensive natural filtering through the rock.

cheers Darrel

 

[PeteA]

The TDS of the RO water going in (after remineralisation) is 95, I'm using TMC powder to remineralise rather than a home brew solution. I did leave a portion (probably 20 litres) of the original water I cycled with in the tank and has had a few doses of ferts in which is how it hit 163 when I checked it the other day. Going to start monitoring the TDS increase with each dose of ferts and see what happens Water change is due on Friday so will be able to see what will happen to the levels too.

The NO3 out of my tap water is nearly always 40ppm+, plus the dGH is around 20. As you say we do have a deep aquifer and most of the water collected by wessex water gets filtered through the many chalk downs in Wiltshire which is why it's so hard Since I've flipped over to RO the live stock in the tank have been more active so I can't justify going back to tap - yup made a rod for my own back there. That said cutting it with tap might be a thought when the current powder supply runs out.

pete