Understanding water parameters

[Majsa]

More out of curiosity than due to any issues, I am trying to understand my water report.

I was wondering already why I have a relatively high PH out of the tap (±8), while the hardness remains in the medium region (8). My KH is around 7. I just read on our water supplies website that they soften the water from GH13 to GH8,5 with natrium hydroxide and sand, could this be the reason? Most people here with much harder water still seem to have a PH of around 7.

Then I realised my EI kit doesn't have MgSO4 in it (it seems I am adding less than 0.1 ppm of magnesium through the micro mix). What is the ideal ratio of magnesium and calcium (for plants, shrimps...), is there such? It seems my tap water has 8 mg/l magnesium in, so with 50% WC I am adding 4 mg/l per week. My plants are doing OK but I guess they could benefit from some extra MgSO4. I use home-made macro and micro stock solutions as per instructions from the EI supplies site, but they don't have instructions for MgSO4. Can I add it to one of the solutions or just pinch some powder in half way the week?

 

[zozo]

Why Ph excactly differs slightly from region to region i do not know. But the ideal pH for drinking water the water companies in our country aim for is pH 7.8 to pH 8.3, but pH7.0 to 7.8 is still acceptable. So if you get 8 + from the tap, your water company actualy is doing a great job regarding optimal drinking water pH conditions. For the aquarium it doesn't realy mater that much, pH 8.5 stil is acceptable and the fish realy don't mind.

I live in the southern part of the Netherlands and my aquarium water also is above pH 8 during the light cycle and drops to pH 7.5 during the night.

For magnesium 2mg/l to 5mg/l are good values, even adding a bit more doesn't realy hurt. For this you can simply buy Epsom salt (bitterzout in Dutch) at the pharmacy or online drugstore. 1 kilo goes between the € 6 and €10 depending where you buy it and will last you a very long time. 1 gram on 100 litre = 1mg/l, that's a tad more than a pinch to get it to 5mg/l

I do it weekly after each water change, drop it in a bottle with luke warm water shake it well and add it to the tank.

 

[ceg4048]

I was wondering already why I have a relatively high PH out of the tap (±8), while the hardness remains in the medium region (8). My KH is around 7. I just read on our water supplies website that they soften the water from GH13 to GH8,5 with natrium hydroxide and sand, could this be the reason? Most people here with much harder water still seem to have a PH of around 7.

The pH of water is a function of it's alkalinity. You must be careful when interpreting the term "KH". The term refers to "Carbonate Hardness" which in turn refers to the amount of Carbonate and Bicarbonate only. These are the standard buffers which affect the waters ability to resist pH changes. However, there are other ions in the water which also have the same effect. It is the sum total of the Carbonate/Bicarbonate + the other ions that determine the total alkalinity.

GH has very little effect on this parameter, however, water that has higher GH coincidentally usually also has higher Alkalinity simply because the dominant Carbonate carrying substance is typically Calcium Carbonate, so that the Calcium affects the GH and the Carbonate affects the Alkalinity.

Hobby grade KH test kits cannot distinguish between Carbonate/Bicarbonate and the other Alkaline ions in the water, so they are really misnomers. They are Alkalinity test kits. We do not know what method was used by your municipality, so we cannot tell whether they accurately measured Carbonate Hardness or whether they measure Alkalinity. So it's entirely possible that the municipality measured true Carbonate Hardness and that the total Alkalinity is a bit higher, which would have the effect of raising the pH.

As you mentioned, the question was an academic one, but many hobbyists worry about these numbers needlessly.
The only danger of pH above 7.0 occurs if ammonia is released in the water such as large number of fish dying, for example. If this occurs when the pH is high then the NH4<=>NH3 equilibrium equation moves toward the more toxic NH3. This potential hazard is kept in check with large and frequent water changes.
We continually advocate performing frequent large water changes, et the same people who worry about pH also seem to be programmed to resist water changes.

Cheers,

 

[dw1305]

Hi all,

I am trying to understand my water report.

Looks fine, and pretty good quality.

There is quite a lot of natrium (sodium) (Na), but that is probably because of your location (Hague?), rather than any sodium hydroxide (NaOH) addition, the temperature suggests it is a ground-water source. Any NaOH addition is just to keep the pH above pH7, the low NO3 value is probably due to the sand filtration.

A result of the CO2 ~ carbonate ~ pH equilibrium is that all water, with any more than a trace of carbonate hardness, will have a pH around pH7.8

The conductivity reading is ~510 microS (/cm) so there are a reasonable amount of ions in solution.

cheers Darrel

 

[Majsa]

Thank you all, very informative! The water indeed comes from the dunes and is filtered through sand. I've noticed the low NO3, when I didn't dose ferts in my QT tank, the limnobium died quite fast while the other plants didn't seem to mind. Well I assume it was mainly due to the low nitrates in the tap water.

I am going to order 1 kg of MgSO4, enough for ages and maybe a foot bath too

 

[Majsa]

I was reading a bit about conductivity but don't fully understand it. Does knowing the conductivity in the tank have any meaning if you are not using RO water and are performing frequent water changes? I am thinking of an open top tank and evaporation, maybe it could indicate the need to make extra water changes (due to build-up) or is this negligible?

 

[zozo]

Does knowing the conductivity in the tank have any meaning if you are not using RO water and are performing frequent water changes?

It can be difficult to understand if you dive in deeply on a chemistry basis.. But simply in layman's terms Conductivity or EC (Electric Conductivity) gives you an indication of how many salts or other words Total Disolved Solids (TDS) you have in the water column. And thats it, it doesn't say what all these disolved solids are it just gives a total of everything. It doesn't tell you very much and if you do frequent water changes there is even less use for it.

But for example say you have a starting point of EC 50 from the tap or what so ever. Than you add dry salts as ferts that are all Solids that disolve and after adding it you will measure for example a EC 120. Than you know you added EC 70 extra disolved solids. This can be calculated back to a total PPM.
All nice but you actualy know that already by knowing how much of which ferts you weekle add in equal amounts than it's a neglectable number. You reset everything anyway with a weekly water change starting over again.

Tho it could give you an indication about when it's time to do a water change in a different maintenance approach. That if you have a starting point of EC 150 after a water change and adding ferts. Than you could say i keep tracking this number and when it reaches EC 180 as your critical point it's time for a water change again. Because not only ferts but also fish waste and topping off evaporated water etc. encreases TDS as well.

So depending on your approach in maintenance schedule it could tell you something and many people use it for that. But i also have one, but do not use it, because it tells me zip. I know what i add and know what i take out at the end of the week and start over again, which is a status quo anyway always measuring the same thing wasting batteries.

 

[sciencefiction]

Does knowing the conductivity in the tank have any meaning if you are not using RO water and are performing frequent water changes?

Conductivity increases because of pollution. If you're not adding fertilisers for example, do water changes but conductivity creeps up and is way higher than that of your tap water, we're talking water deterioration and water changes not big enough and often enough..

So let's say you started a tank and initial conductivity is 100, should be similar value to your tap at that stage... If after a year it is 300, then one has done a pretty bad job at maintaining the water of that tank....Even if you're adding fetilisers...,for example I add micros to one tank, one should still maintain a relatively constant conductivity level over prolonged periods of time, close to that of the tap water...I do, so I know it can be done easily.

Now imagine a tank that's not maintained properly for years....All sort of odd things start happening....Fish start dropping for unknown reasons, Water changes make fish "unhappy". New fish are always "diseased" and some die soon after introduction. Some fish do better than others.... One doesn't have many old fish and the fish turnaround is high...etc..etc...One uses nitrate removers, etc..and keeps saying water is perfect, no ammonia and nitrites, nitrates below 20....but can't figure why fish aren't doing that well....blames it on the bad fish shop they purchase the fish from...which had only spent a few weeks in said shop....

 

[Majsa]

Thank you, that makes a lot of sense. I will stick to the weekly water changes, that should cover it mostly. I still feel tempted to get a conductivity meter, not out of pure necessity but just to check once in a while...another gadget to have...although it somehow sounds contradictory to the principles of EI (is it?).
Then think it is not useful to compare tanks (different soils or ferts), just initial values vs. values later on.

I really appreciate you all taking the time to write these thorough replies, I am learning a lot here!

 

[sciencefiction]

.although it somehow sounds contradictory to the principles of EI (is it?)

Not necessarily. The concept of EI is to provide enough nutritients for the plants at any one time. Which is normally a constant when the plant mass has reached its maximum in the tank. It is not actually a wildly swinging variable...A certain amount and type of plants will consume so much at any given time/week.

A properly maintained EI tank may require a lot more than a regular 50% weekly water change to be in top condition so in reality EI tanks can be healthier long term as people take the extra steps to do those large water changes more often. Thus accumulation of anything doesn't really happen...at least not organics as otherwise one will have an algae ridden tank and not much of a tank to show for...

Then think it is not useful to compare tanks (different soils or ferts), just initial values vs. values later on.

Yes. Your source water is normally what determines initial values. There isn't much you can do about that. But there's a lot you can do about any subsequent pollution/accumulation and shifts in water chemistry.

.

 

[Jack G]

Sorry to jump on this thread, but I also have a question regarding my water report.

I'm in the South East (Southern Water) and my report states that the nitrates in my tap water are around 31ppm.

Is this value likely to be relatively stable, or could that fluctuate regularly?

I've been dosing 50% EI in a relatively low light tank, but I don't want to be needlessly adding extra Nitrate to my tank if it's not required.

Should I continue with regular dosing or am I probably alright to scale back any NO3 dosing?

Thanks
All the best
Jack

 

[ian_m]

I'm in the South East (Southern Water) and my report states that the nitrates in my tap water are around 31ppm.

Great. Ignore it. This is the water companies sampling point on a particular day not your tap today. 99.999% of people of roll their own EI (not strictly EI then) all end up with plant nutrient issues, usually nitrate, magnesium or iron deficiency issues.

Dose as per EI (50% in your case), work with the water your have. Inorganic sourced nitrates have to be in the order of 1000's ppm before you will have fish issues.

 

[dw1305]

Hi all,

I'm in the South East (Southern Water) and my report states that the nitrates in my tap water are around 31ppm. Is this value likely to be relatively stable, or could that fluctuate regularly?

They usually vary a bit during the year. It depends on rain-fall and whether the major source is from domestic sewage treatment or from agricultural run-off.

Have a look at <"EA: Underground, under threat, the state of groundwater in England and Wales">, it is quite a sobering read.

.........Groundwater samples can contain a mixture of water of different ages. Water that stays near the top of an aquifer might only be underground for a month, but some of the deepest water is thought to be millions of years old. Water in the Chalk in the south east of England can be 20,000 years old, originally falling as rain towards the end of the last Ice Age.4 The unsaturated soils and rock above groundwater can protect it from pollution. They often act as a filter, sieving out harmful chemicals and bacteria. But in some places groundwater is closer to the surface, so some contaminants do get through......

cheers Darrel

 

[Jack G]

Great. Ignore it. This is the water companies sampling point on a particular day not your tap today. 99.999% of people of roll their own EI (not strictly EI then) all end up with plant nutrient issues, usually nitrate, magnesium or iron deficiency issues.

Perfect! Will continue as normal. Thanks Ian.

Have a look at <"EA: Underground, under threat, the state of groundwater in England and Wales">, it is quite a sobering read.

So my fishtank could potentially have million year old water in it? I assumed some of the chalky stuff we get down here must of been sitting around in the cliffs for a while haha.

A brief glance at some of that report seems to suggest that we are seeing increasing levels of Nitrate in our water supply?

Best
Jack