# Where can I get my tap water tested?



## tyrophagus (12 Mar 2011)

I have had some algae problems, currently GSA and BGA.  My CO2 and flow is fine - UP atomiser on separate 3000 lph powerhead circuit in addition to the 1700 lph filter. Spraybar. 200 l tank.  Dosing EI for 300l.   I have plants that show nutrient deficiency and crypts that regularly melt their new leaves.  I have par meter and the substrate par is about 40.  50% water change at least every 7 days, recently every 4 days.

I think my nutrients are messed up and I blame my tap water.  The local water report does not mention phosphate or magnesium.  I think nitrates are fine straight from the tap

Where can I get my tap waters Phosphate and magnesium tested at a reasonable price?

Any help trying to  establish my tap waters baseline levels appreciated.


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## George Farmer (12 Mar 2011)

Reef owners frequently test for PO4 and Mg.  I understand there's some accurate kits available.  Might be worth posting on a reef forum to see the best kits.  Ultimate Reef is the UK's biggest forum I think.  

A shop specialising in reef may be able to do a one-off test for you for a small fee.

Edit - just done a quick search and this kit is highly rated - http://www.aquatics-online.co.uk/catalo ... st-kit.asp

Salifert do a Mg kit, but I'm not sure if it's for frewhwater.


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## dw1305 (12 Mar 2011)

Hi all,
Kit George suggested is OK, I'd be very interested in the result. But you don't really need to test, the NO3 level is pretty high, so a combination of agricultural run-off, sewage works and the orthophosphate added (to control Pb levels) will almost certainly make the phosphate value high as well. The Mg level will be low, and the Ca:Mg ratio very high so adding some more  Mg (from "Epsom salts" - MgSO4.H2O) should help plant growth. Even if you have enough Mg all ready it won't do any harm. 

cheers Darrel


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## tyrophagus (12 Mar 2011)

So using james's dosing calculators I can add 4 tsp Epsom salts to my tank at every water change.  That should give 10 ppm in my 200 l. Would it matter if I changed 50% 4 times a week say and added this much mg at each change?

Dosing normal EI Levels will keep my npk at optimum levels.  

How does a large water change more than once a week (say 50 - 70% twice weekly) affect the EI dosing?  Do you just do the water change on the day you are dosing macros and leave the EI amounts the same?

Thanks again for your help.


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## dw1305 (13 Mar 2011)

Hi all,


> That should give 10 ppm in my 200 l.


I can't really answer the EI question, but dosing at 10ppm if you have an Mg deficiency it should show very quickly, magnesium is mobile within the plant, so you should get a very quick "greening" response at the shoot tips if magnesium was the limiting nutrient.

cheers Darrel


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