TDS help with electronic algae remover??

SanjayB

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10 Feb 2020
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8
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Watford
Hi,

I need some help with TDS which I think might be too high in my tank??? its a ADA 60p with Eheim 250t and co2 at bare minimum. I have been using the EI method for dosing except doing water changes every 2-3 days due to the algae.

I have been using tap water in my tank with Seachem prime for a few weeks with no problems. Recently I introduced fish and it seems like this has spurred on some algae growth. I can see patches of green on my rocks. I was thinking about buying an electronic algae remover until I read their instructions and it said not suitable for water with TDS over 500.

I checked my tank water and it is above 600. Is that normal? I changed the water about 3 hours ago from the tap?

My cold tap TDS is 480 and hot 550 (Hot I suspect higher because we have a water softener).

Should I do water changes with RO water instead from now on and add the EI macro/micro as normal?
 

SanjayB

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10 Feb 2020
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Watford
i have checked the GH of my water and it is 1. Therefore my tap water is low Gh (soft) but high TDS (500!?). Is there any way to reduce the TDS of my tap water, or should I just use RO water for the time being?
 
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Woking, UK
It’s important to remember that your water softener isn’t “removing” anything from your water as such; it is merely swapping the calcium (and magnesium) and replacing it with sodium. The associated carbonate and bicarbonate is staying in the water.

Loosely speaking, GH is a measure of calcium and magnesium, whereas KH is a measure of carbonates and bicarbonates. It therefore follows that softened water should have very low (or even zero) GH, because the softener should have swapped most (or all) of the calcium and magnesium ions and replaced them with sodium (which isn’t included in GH). It is possible that your softener has been configured to mix a little unsoftened water back in. However, your softener has done nothing about the carbonates and bicarbonates, so the KH of the softened water should be identical to your unsoftened water.

Now, it’s also important to understand that TDS is a total of all the substances that cause KH and GH, plus a load of other things as well, including nitrates, nitrites, ammonium, dissolved organics, etc etc. Loosely speaking, TDS is a measure of the “purity” of your water, but a high TDS reading tells you nothing about what’s causing it.

Personally I would ignore your softened water. You’re not going to be using it in your aquarium because the sodium that your water softener has swapped into the water is not good for fish and plant health. So let’s disregard your softened water, and make sure you’re only measuring unsoftened water (your cold kitchen tap will normally be unsoftened).

You mentioned that your cold tapwater has a TDS of 480. Most of that is likely to be hardness. Tapwater is allowed to contain up to 50 ppm of nitrate, which will contribute a bit to the TDS. You can find out from your water company’s web site what the nitrate content is (and also what the calcium content is). But the vast majority of that TDS is hardness.

But then you said that your tap GH is only 1. That is highly unlikely if you’re talking about Watford, and is inconsistent with a TDS of 480. Are you actually quoting the GH of your softened water? If so, let’s disregard your softened water to save confusion. Let’s only talk about your unsoftened tapwater.

You asked whether you should use RO. Well, yes you can, but there’s a cheaper option. Why not use rainwater? It’s free, and is largely free of pollution these days. It will have very low (or even zero) GH and KH readings. You could mix this with some tapwater to give you the approximate hardness you want. For example, in Woking I mix 10 litres of rainwater with 2 litres of tapwater to give a GH and KH of about 4°. I then boost the GH by a few degrees by adding Epsom salts (magnesium sulphate), because in Britain nearly all hardness comes from Calcium, and our water lacks a decent source of magnesium (for plants and shrimps). If you make up a stock solution of 44 g/l of Epsom salts, then dose 1 ml of that stock solution per litre of tank water (or water change water) that will raise the GH by 1°.

Using rainwater is the easiest way of bringing your TDS down. Your tapwater is likely pretty hard, so you’re starting with a high TDS and you’ll never bring that down unless you dilute with “purer” water. But I would make that change gradually over the course of several water changes.
 
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Joined
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Dorset
I thought our tap water was bad enough at 280. A TDS of 480 sounds very high, have you checked the published data from your water supplier? I’ve been using rainwater in my Nano’s with great success so far. Good plant growth and the shrimps are breeding like mad. No need for things like water conditioner either just a quick squirt of fertiliser every now and then.
 
Joined
3 Jan 2016
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297
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Woking, UK
I thought our tap water was bad enough at 280. A TDS of 480 sounds very high
Yes, it does sound suspiciously high. In Woking our tapwater is classed as “very hard”, and I’ve just put new batteries in my TDS meter and got a reading of 262 out of the tap.

I’d be very surprised if Sanjay’s tapwater in Watford were hugely different, so something is amiss here.

Sanjay, are you sure your TDS meter is working correctly? Does it have fresh batteries?
 

dw1305

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7 Apr 2008
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nr Bath
Hi all,
Yes, it does sound suspiciously high. In Woking our tapwater is classed as “very hard”, and I’ve just put new batteries in my TDS meter and got a reading of 262 out of the tap.
It depends a little bit on time of the year and how warm the water is. Highest values are normally in the summer when the water is warm and we haven't had much rain.

I don't think they are <"unreasonable values">, our tap water comes from a deep limestone aquifer and would be pretty consistently about 600 microS (400 ppm TDS) (divide conductivity by 2/3 to get ppm TDS).

I typed "GU15 5HH" into the web page and in the additional readings it gives "electrical conductivity":

Min: 559 microS
Mean: 636 microS
Max: 741 microS

cheers Darrel
 
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