What to test for rodi water

[no1bubba]

I am getting diatoms after every water change (20% weekly) tank is 5 years old with a move up from 75 to 125 (moved everything but the sand and added 35 lb new pukani (cured 4 mo.) rock. Went through the regular cycling and the diatoms once lasted about 4 weeks. Now every time I do a water change I have diatoms again. So I want to check my RODI water but I do not know what to test it for. Also just found out that I am on my second round with cyano. Cleared it up once with chemclean and it is back on the very tops of the highest rocks and coral. My phosphate is 14. In between football and nascar can someone tell me what I am doing wrong. Thanks, Bubba

 

[kirru]

Have you checked the dissolved solids in the RODI water?
Check your phosphates in the RODI if you haven't.
That's probably where it is coming from.

 

[no1bubba]

Thanks, will check after lunch. Bubba

 

[porpoiseaquatics]

You're picking up phosphates from somewhere if you are getting a reading of 14. You need to get a TDS meter for your RO/DI water. That tells you when your chambers need changed. Ideally, you should get 0 TDS on the output end. If you're getting more than that, then cartridges need to be changed.

 

[jef4y]

Yep, as they mentioned, check your RODI for phosphates and TDS. Most likely you need new DI resin or a full compliment of filters.

Phates that high are where your problems are coming from. Find the source and remove it.

 

[rdnelson]

I don't disagree about getting the phosphates down but that should not be the cause of the diatom. Diatom feeds on silicates. You are getting silicates from something. Could be the RO/DI (0 TDS would indicate no silicates) or it could be leaching out of the rock. Are you on a city or county water supply? If so, ask for a report and specify you want to know what the concentration of silicates are. If you are on a well, I bet you have high concentrations and your RO/DI was doing the job but needs media replaced. But then I could be wrong.

 

[no1bubba]

Just did my Hanna checker and I come up with 1.34. Did a second test and it was 1.38. City water here, honestly forgot when I changed out my RODI filters but will do that in the morning. How long should I let the RODI water run before testing it again? Thanks again for all the help. Bubba

 

[kirru]

If you change the filters results should be immediate. If you have a container that hold ready made freshwater then until you empty the dirty water out you wont see positive results for a few weeks, depending on how much you use it. Mine recently shot up the TDS meter built in to the flow of the RODI but then it dropped back to zero. Of course I could see the DI resin change so I know where the TDS readings were coming from.

 

[no1bubba]

What is a TDS meter? Can it be purchased at the local exotic fish store? How much $$$$?

 

[KrisDeitz]

Total dissolves meter. Should be able to get one off the net for a cheap price

 

[rdnelson]

Here are some good ones at a decent price from one of our sponsors. The $40 in-line is a good unit.

 

[no1bubba]

Added some PHOSBAN for the hot tub to my ATO earlier today and just tested it 9. I will be changing out the RODI in the morning. Thanks again, Bubba