RODI Auto-top-off purity

[wmcguire]

Hi,

I'm questioning my auto-top-off system that I have direct from my RODI into my sump. I've been experiencing a lot of green algea since I hooked up the system a few weeks ago. It may be coincidental, but I heard that auto-top RODI methods may not be as pure as expected.

My PH is ~7.8, AK = extremely low, phosphate = zero.

What else should be monitored? also, PH of 7.8. High? Or, maybe the test kit doesn't go lower, not sure.

Please advise, also, if you have the same type of set-up, any such issues?

 

[TomD]

I would focus more on that low alk and get it up to normal range. What is your range?

 

[stevenp]

Have you checked the TDS level of the water coming from the RO unit?

When did your PH check at 7.8? It will rise during the day while the lights are on and fall at night while the lights are off. I don't think a reading of 7.8 at night is that uncommon. As long as it rises to 8.2 or so during the day I wouldn't think it would be a problem.

How low is your Alk? Can you be more specific?

 

[delta]

Do you have your RO\DI turning on and off at every top off cycle with a float valve?
If so you're top off quality is less than optimum. your water quality will degrade extremely fast.

RO\DI units are designed to make larger quantities of water. It is best to make say 5 gal + and work your top off from that actually safer too.

I make 45 gals\week then I fill a 5gal bucket with about 4 gallons to feed my auto top off. so even if it pumped all the contents into my sump with the size of my system it wouldn't throw things off too much

More than you asked for but it what came out

 

[TomD]

I did not know that at first but now I make 10 gallons a shot. I do not have my RO hooked to my topoff.

 

[wmcguire]

I may have been a bit mis-leading with my readings. The readings that I quoted above are from the RODI water ONLY (coming out of the 1/4" into my sump). I'm trying to check and see if my RO is degrading by having it on-off-on type of system.

I considered the 5g bucket method at first, but found a neat dual switch that appears to be well built and thought that I would chance a disaster by hooking the Ro direct to my pump (using no 5g bucket). So far, so good, but the water quality is in question. The RO PH is what was reading 7.8 (but this is with zero alk, thus is almost not valid).

I just want to monitor the RO going into the sump for degradation - I need to be convinced that the money spent was a waste (for the dual switch and pump). If I can measure the right parameters of the RODI and show that the quality is degrading, then I change plans - most likely go to the 5gal reservoir method.

Please let me know your further thoughts

Thanks All

 

[delta]

Test it for TDS, PH and ALK are not tests you need to test your top off water for

It will degrade with constant on off short fills. Your TDS will go up fast you will always be filling High TDS water.

 

[TomD]

Greg you are right. The reason I recommended testing alk was because he said about algae and alk-"extremely low"