power sand?

[trong]

in january i rescaped my 80gal and instead of just flourite as substrate which i've used for 8yrs. i added powersand as underlayment.
i keep kh low between 2 and 3 and prefer gh at 5 or below(species requirements). i do my 30 gal water changes using R/O and add Ca, k2so4, kno3, kh2po4 weekly. i dose macros and micros minus Mg alternating every day. my ? is how long will power sand leach Mg into my tank for. I never add it and my lamotte kit alway says between 4 to 6ppm mg and i keep ca at 20 to 22ppm. everything is growing good. I'm just curious about mg or power sand i guess. It's been 7 months without mg addition. your help is appreciated.

 

[Tom Barr]

Some Mg might be coming in from another source, eg TMG, some might be making it through the RO etc.

Check those first.

Regards,
Tom Barr

 

[trong]

thank you for your reply i do appreciate your time and experience. My trace does not contain Mg. Its DNF from canada. my R/O water reads 2ppm tds. if it were there would that number not be higher? the water i add for evaporation is DI water. I'm guessing this situation doesn't make sence to you either. I don't know anything or at least not much about power sand and i was hoping that was my answer. I have no decorative rocks but i do have 2 large pieces of wood but they have been submersed for 8 years. I'm stumped but open to suggestions!

 

[Tom Barr]

You might try testing and calibrating the GH test kit with some DI water and MgCO3 or MgSO4.

At 4ppm of GH, that's pretty low, the resolution is only 4 ppm or so with the Lamott test kit...........

Might be test kit resolution error.

They make really low levels of Ca and Mg test, but they are colorimeter based. Not sure if there are any that are really decent for test kit colormetric types.

Hach might have one.

Still, I think at such low levels, I'd not believe and put too much faith into the readings.

This is a common mistake for many.
Some leaching or binding from the sediment might alos play some role as well as plant leaching, but this low level would typically get used up pretty fast.

Expired reagents is yet another suspect.

Regards,
Tom Barr

 

[trong]

good morning tom

i'm a little confused on how to calibrate GH test. i have the stuff you mentioned. My gh of the tank is 5dkh

 

[Tom Barr]

You need to make a standard reference solution of Mg++. Say 1ppm, 5ppm and 10ppm.

You need a an accurate scale and weight out enough to make say 1000mls of 100ppm Mg++. Ppm = mg/l

Then dilute this using DI water to get 10ppm, 5ppm and 1ppm Mg.

Make 100mls of 10ppm, you dilute 10mls of the 100ppm solution into 90msl of DI water etc.

Then repeat on down the line.

Not easy but this will tell you if the kit is accurate.
Right now you cannot be certain, it's a question you do not know.
The above will answer it assuming you do the calibration solutions correctly.

Test kits can help, but more folks worry and then never bother calibrating the test kits, so I generally tell folks not to worry too much about the test kits or use them.
They cause more issues and questions than they answer/resolve for 99% of the aquarist.

And anyone can understand why that is........few want to calibrate and deal with all that, but that's what needs to be done to be accurate and confident about the reading, I have to do this when I test anything at the lab.

That way I know vs assuming and guessing.
Many aquarists will argue with me about testing etc, then never really do this step

They want to have their cake and eat it too and also act like they have some advantage over folks that do not use test kits. ADA does not really deal with them, nor do I, we seem to do pretty good.

I also do test, but generally for experimentation purposes only.
It's a lot of work so I do not do it as a daily practical routine.

You can use the practical approach also, add a little MgSO4 and observe, while making sure the CO2, other nutrients, water changes etc, light are all in good shape so you do not assume Mg is the cause when it might be poor CO2 etc, or you should have done a trim and now have 3x the plant biomass and higher uptake rates.

Regards,
Tom Barr

 

[trong]

thanks tom. if i'm reading between the lines wrong let me know. it's impossible for powersand after 7 months in the tank to be leaching Mg into water. and without calibrating test kits its silly to be using them at all even if just for a guild as opposed to a rule

 

[trong]

on a totally different subject. awsome 180 starfire. I will in the future plum my tanks this way. You have set up some truly great tanks i've seen. Your sight has been and is a sorce of inspiration and information on the path to clarity.

I sell alot of my plants to Guy at albany aquarium and have been for some time. i hope to one day run into you there. it seems i've just missed you acouple of times

 

[Tom Barr]

thanks tom. if i'm reading between the lines wrong let me know. it's impossible for powersand after 7 months in the tank to be leaching Mg into water. and without calibrating test kits its silly to be using them at all even if just for a guild as opposed to a rule

Well, it's a trade off, how much do you want to be be sure about those test kit readings?

Unless the companies that sell them make standard reference solutions included, I do not think there's much that can be done.

SeaChem is about the only company that does this.

If they where smart, they'd give the users a small amount of 1-5-20ppm or a larger bottle of say 100ppm for Mg, Ca, NO3, etc and then explain how to dilute. This way they'd know how accurate the test really are and have a comparison.

Making the reference solutions and adding them in small bottles in the test kits does not cost much more, and then they could add say 5$ more for a 50 cent item.

This would help a great deal.
But what do I know........

I cannot not say for certain that PS is not leaching Mg, it's just unlikely and ADA AS has a lot of Mg binding CEC. Some pumic might have high Mg in it and under acidic conditions, or reducing conditions, it might leach.

Still, seems like a lot if no source of Mg is being added or not.

Regards,
Tom Barr

 

[Tom Barr]

on a totally different subject. awsome 180 starfire. I will in the future plum my tanks this way. You have set up some truly great tanks i've seen. Your sight has been and is a sorce of inspiration and information on the path to clarity.

I sell alot of my plants to Guy at albany aquarium and have been for some time. i hope to one day run into you there. it seems i've just missed you acouple of times

Well , come to the open house in Sac this Aug, see SFBAAPS open house announcement.

Sat Aug 21st.

Regards,
Tom Barr