Tunze TDS reading 006 after membrane change

[MrsHaggis]

We have an aqua pro RO water system (which I think we should change for an RO/DI solution). We were having a bit of an algae problem so we bought a Tunze TDS monitor so that we could see what the reading for the output was. It was 000 on the old membranes, but then quickly increased to 003 (they were quite old) so we bought two new membranes and installed them. We have ran about 6 to 8 gallons of water through the system now but the lowest output reading we get is 006.

Do we just have to run more water through, have we installed it wrong, are the new membranes not working properly?

Any ideas are most welcome.

Thanks

 

[rvitko]

Typically an RO membrane is not fully hydrated until it has been in use for 2 weeks. It doesn't need to be in continuous use but it should be run for a few hours and allowed to stay wet. Even 6ppm is a very good result from an RO, 0 or 3 is exceptional. I think the cause of the algae is probably not the source water, more water changes and cleaning of the tank should reduce it, what kind of algae is it? It is also possible the tap water has more pollution if it rained recently, silicates and some minerals are not removed well by RO. Do you know what kind of membrane it is that you have? We have used 2 brands, GE Osmonics and now we use DOW Filmtec, the DOW is the newer one and generally the best that is available.

 

[MrsHaggis]

We had a big hair algae problem (green, black and red), some neomeris, some red algae....generally just lots and lots of it but mainly green hair algae. We have cleaned up about 90% of it manually and slowly the snails are doing the rest.

I think it was a combination of too much light, too much food (the neighbours were feeding over the holidays) and no water changes for 2 weeks but we also wanted to make sure the water quality was as good as possible.

We have and AquaPro Pure RO System (the LFS did not have any Tunze ones available). We have changed two of the 3 membranes : Dirt and Sand Reduction and Taste and Odour Removal. We have a 3rd membrane that we did not change; just didn't think to ask the LFS why we shouldn't change it and have only now thought of it to be honest (feeling a bit stupid).

You are the first person to say that we need to wait a few weeks though - which sounds hopeful.

Our input TDS is 284 (or thereabouts, it can go up to 330), and our output is now sitting at 019 which is a big increase from the 004 we had yesterday (it decreased from 006).

We are thinking of installing a DI part of the system, or replacing the whole thing for an RO/DI system that can keep up and will give excellent results. Which Tunze one would you recommend?

 

[rvitko]

My experience with hair algae is high pH and KH will kill it over a few months. Probably the food decomposing lowered the KH and pH and also added nutrients. Try to keep a KH of 12-14 dKH for a few months. It sounds like you changed the carbon and not the membrane. The carbon only removes the chlorine and some pesticides and contaminants from water but not nitrate and phosphate and silicate. You would need a new membrane, 8550.510 to improve the TDS, but your results aren't bad, I wouldn't change it if TDS on output was less than 25. DI is not necessary, I would only use DI for the first fill of a new tank. DI mainly removes silicate that the membrane does not, but you have no diatoms and I don't think it will help for small water changes and top off. We do have a refillable DI it is part 8550.600. The main reason to use DI in my opinion is to prevent diatom problems in a new tank.

 

[MrsHaggis]

So many conflicting opinions.

Some guys on here would not use water that has a TDS of more 003 and insist on using DI. And everytime you post an algae problem it is blamed on not using RO/DI water. Are they just being over cautious?

 

[rvitko]

I would always use RO, RO removes 92%+ of most contaminants but only about 80% of silicate. DI though to me seems like a big expense to remove the remaining 10% and if that is the only nutrient going in the tank and you change 10% it is such a small amount that the algae might have food for 1 or 2 days.

 

[shawnz28]

Just curious another big question for me orther than what is the customers water souce for hair algae is what is your Phospahate in the tank testing at? High phosphates are usually a common cause, but tanks with large amounts of hair algae can be "tricky" as they at times will actually test low for PO4 as the algae has bound it up.

 

[MrsHaggis]

Hi Shawn , Actually thought I had answered this.

At first we were testing 0 for Phosphates but then on removing 95% of the Hair Algae by hand we started testing at 0.1 for Phosphates. I think the GHA problem came about over the holidays through a combination of too much light (8 hours per day), too much food (neighbours were feeding) and no water changes (we were in Scotland for Christmas). We are still testing high for Phosphates and that is because we cannot do enough water changes (still waiting on the part being delivered for the RO system).

Once I have the new membrane I'll be doing about a 50% water change over the course of 5 days to see if we can bring down the phosphates. I have reduced the light to 5 hours, feeding to every two days.

Cheers
Fiona