• You are viewing the forum as a Guest, please login (you can use your Facebook, Twitter, Google or Microsoft account to login) or register using this link: Log in or Sign Up

Rain water from gravel roof causing problems?

Yes. The last ICP report shows 44 mg/L Ca. With 50/50% waterchance I add 22 mg/L which I assume is more than enough.
Mg is only 5 mg/L. So I have to add some Epsom salt. Next time I will adjust this amount to total Ca:Mg ratio of 3:1.
 

Attachments

Sanniejop said:
This seems pretty accurate.
Click to expand...
Sure. However, cheap wide-range TDS meters tend to be off at the very low range. Unless it's a higher end lab grade device such as Hanna instruments optimized for low-range, I wouldn't really trust a reading much below say 5-10 ppm.

Cheers,
Michael
 
Last edited:
Well it is of more interest what it measures in the tank. In the range of my tap water (220) and my tank (currently 365) it is quite reproduceable in what it measures. So it gives me some indication of the tank status. This TDS stuff is al quite new to me but it gives me a feeling that you have some sort of control.

I am planning an upgrade to a 450L tank and my wish is not to be needing to do weekly big water chances. So my hope was to be able to monitor the status of the tank and know when it is needed to do a water chance. I read somewhere that a rise of 100ppm above the value of the fresh WC water is a good trigger point. Is that correct?
 
Last edited:
MichaelJ said:
cheap wide-range TDS meters tend to be off at the very low range. Unless it's lab grade device and low-range, I wouldn't really trust a reading much below 5 ppm.
Click to expand...
True, but whether it is 3 or 4 or 5 ppm it is still very much in the clean water range and suitable for using in his tank.

I guess a good way to test the meter through the whole range would be to start with the test solution at 2000 and dilute it 50/50 with rainwater, test again and repeat/test.... repeat/test until you reached the very low range.
 
Maf 2500 said:
True, but whether it is 3 or 4 or 5 ppm it is still very much in the clean water range and suitable for using in his tank.
Click to expand...
Sure thing - just pointing it out to make people aware that with cheap wide-range meters at the very low range, you are mostly measuring around the noise floor. I am sort of a TDS aficionado 🙂 For tank measurements, far above the noise floor, it's such a great tool to establish a datum and monitor drift, wide swings in water source etc. the only tank measurement I really make on a regular basis and trust. It definitely has its limitations; you won’t be able to detect a spike from say organic waste that are not fully decomposed (when it is, you will - contrary to popular belief), a spike in ammonia or other potential hazards well inside the margins of error such as copper or zinc that easily gets lethal at say 1.0 ppm, but it gives you something quantifiable in addition to your eyes and common sense. 😉

Cheers,
Michael
 
Last edited:
Sanniejop said:
I am planning an upgrade to a 450L tank and my wish is not to be needing to do weekly big water chances. So my hope was to be able to monitor the status of the tank and know when it is needed to do a water chance. I read somewhere that a rise of 100ppm above the value of the fresh WC water is a good trigger point. Is that correct?
Click to expand...

A 100 ppm drift that would be excessive in my opinion. You will have to look at the cumulative change and where you hit the equilibrium:

equilibrium_tds = (tds_increase / (wc_percent / 100)) - tds_increase + wc_tds

Theoretically speaking, if your starting point is water at 220 ppm and it increases by the application of fertilizers, leaching hardscape and more detrimental decomposed waste etc. to 320 ppm and you change say only 25%, the equilibrium TDS will eventually (after a number of water changes, after hitting the +100 ppm increase) reach around 520 ppm - thats huge. If you change 50% the equilibrium will be closer to 320 ppm. Of course, you can throw in an extra (or larger) water change once in a while to keep the TDS more reasonable (i.e. get rid of excess).

You can play with the numbers; If you go for say a 30 ppm increase as an indicator and do a 25% WC thats going to stabilize around 300 ppm which, while still somewhat high depending on livestock, is a much more reasonable number.

In practice your milage will vary. WIth my own two tanks its pretty consistent though.

Cheers,
Michael
 
Last edited:
Hi @MichaelJ ,
Thanks for your reply. As I said i am quite new to this. So what is at all a reasonable tds value for life stock and/or plants?
Is my tap water already on the high side?

Currently my plan was to do 50/50% water/rain water changes of 30%, which will have an average tds of 110.
Remineralisation gives around 10+ ppm extra. And I was thinking to do the next change when the tank hits 220ppm. Depending on how much it drops after a water change (and the increase by the reasons you mentioned) it will take a certain time before the next water change.

Is it posible to balance the increase by fertilizers with plant growth absortion? I am hoping to come out on an as low as possible WC frequency for my planned 450L tank.
 
Sanniejop said:
Hi @MichaelJ ,
Thanks for your reply. As I said i am quite new to this. So what is at all a reasonable tds value for life stock and/or plants?
Is my tap water already on the high side?
Click to expand...
No, unless you plan to breed picky soft water species or keep sensitive shrimps, a very gradual change from say 120 to ~200 ppm is not too bad if most of the delta is made up of fertilizers and not just decomposed waste. Natural water ways unless polluted or naturally very mineral rich, will have a much, much lower TDS - which is usually unnecessary and impractical for the average hobbyists to obtain and maintain.
Sanniejop said:
Is it posible to balance the increase by fertilizers with plant growth absortion? I am hoping to come out on an as low as possible WC frequency for my planned 450L tank.
Click to expand...

You can definitely decide to provide less fertilizers and see how the plants react and take counter action on signs of deficiencies but it’s a tricky balance especially as the tank grows in and demand varies. In general, most (including myself) will usually advise beginners to stick to a reputable all-in-one fertilizer and follow the instructions that’s comes with it. In the long run with a 450L tank that may become a bit expensive, but that’s a bridge to cross when you get there.


Cheers,
Michael
 
Last edited:
You must log in or register to reply here.
Back
Top