Heckel Water conditions

[NanDiscus]

Illumnae,

I just read your post further up about the RO unit you're using. If your feed TDS is 80-90 and the product water is 9ppm it means, that you either have a not-so-good membrane or -and this is more likely- insufficient feed pressure. I would strongly recommend getting a pump to get the maximum out of the RO-unit, because with such low TDS feed water and 90-100psi on the membrane your product water should be very close to 0ppm. With the amount of water your project requires, the costs of replacing the DI-resin will exceed the initial investment of buying a pump very quickly.
Just a thought...

Nandi

[jimg]

Illumnae,

I just read your post further up about the RO unit you're using. If your feed TDS is 80-90 and the product water is 9ppm it means, that you either have a not-so-good membrane or -and this is more likely- insufficient feed pressure. I would strongly recommend getting a pump to get the maximum out of the RO-unit, because with such low TDS feed water and 90-100psi on the membrane your product water should be very close to 0ppm. With the amount of water your project requires, the costs of replacing the DI-resin will exceed the initial investment of buying a pump very quickly.
Just a thought...

Nandi

Something does sound off. I have water fed at 45lbs, tds of approx 250 and my ro tds is about 09 with 100 gpd membranes. 90-100 lbs pressure seems way to high anyway.

[illumnae]

Thanks for the thought, I have no idea what my feed pressure is as I don't have a PSI meter. However, the membrane I'm using is supposed to be 90-92% rejection. Isn't it right that my RO water will come out at 8-9 TDS if my input water is 80-90?

[NanDiscus]

Something does sound off. I have water fed at 45lbs, tds of approx 250 and my ro tds is about 09 with 100 gpd membranes. 90-100 lbs pressure seems way to high anyway.

Jim, if the membrane you are using is a bog standard TF-1812 of some sort, then 45psi is somewhere near the low-end of the pressure range at which it should be operated. The quality and the quantity of the product water vs. the amount of wastewater are all much better at higher pressures. 100psi is the upper limit for these membranes, at which a 100gpd RO can (under ideal circumstances) produce up to 120 gallons a day. Those who are saying that low pressures are OK, want to sell you a replacement membrane a.s.a.p. If the pressure is right, quality membranes can go up to 4-5 years without any problems. My own 300gpd unit has been running for about 5 years, the feed water is around 360ppm, the product water is 2-6ppm, depending mainly on the temperature.

Illumnae,
A pressure gauge is a handy little piece of kit to have on every RO-unit. It should not cost more that 5-10 dollars to buy one and it's well worth it. Also, most good membranes have a rejection rate of 96-98% on average and again - with decent pressure on tap they can go up to 99.5%. It also depends on what sort of dissolved substances you your mains water contains.

N./

[tacks]

Hi Since you are trying to keep a low PH have you ever tried adding muratic acid to your holding tank? Just an idea I have used for Altums Ed

[illumnae]

Illumnae,
A pressure gauge is a handy little piece of kit to have on every RO-unit. It should not cost more that 5-10 dollars to buy one and it's well worth it. Also, most good membranes have a rejection rate of 96-98% on average and again - with decent pressure on tap they can go up to 99.5%. It also depends on what sort of dissolved substances you your mains water contains.

N./

I think I know the problem. I read your post here:

http://forum.simplydiscus.com/showth...807#post661807

You said that RO membranes take time to reach their full efficiency. My 8-9 TDS measurement came as I was flushing the system. First time use. As of now, I've had the system for less than 2 weeks. I think that's why it isn't performing to its full potential yet.

My water pressure from the tap should be fine. On a 100gpd membrane, it takes about 11 hours (slightly less) to fill my 52gallon barrel. Hence, it's actually producing slightly more than the rated 100gpd. I think it should be fine?

Hi Since you are trying to keep a low PH have you ever tried adding muratic acid to your holding tank? Just an idea I have used for Altums Ed

I wish I could. Singapore government controls chemicals very very tightly. I can't even get KNO3 for fertilizing my planted tanks here, let alone muriatic acid

[Apistomaster]

An aquarium RO unit ought to reject 97-98% of the TDS so yes, I agree with the remarks by by others that there is a problem. RO membranes are made for different uses and some may not be optimized for the kind of purity desired in reef tanks and projects like your Heckels.
The kind of performance most of us expect from our RO units is so good that the use of a final stage DI cartridge is overkill. They are most useful when one is trying to produce acceptable laboratory water purity levels.
Even at the lower end of acceptable incoming water pressure the rejection rate should not suffer although the volume of water produced each day certainly would.

It is unfortunate that you did not have more options available to you in Singapore but until recently hobbyists in Singapore enjoyed water which was well suited to most soft water fish.

If you can at least produce RO water which is not more than 20 ppm, your Heckels will be fine. Lowering the pH of the large amounts of water needed for the water changes can not be done with peat, or at least without a huge peat filter and even then it is hard to get the pH down to 4.0 to 4.5 without using a strong acid to drop it a couple points.
Remember the pH scale is logarithmic and their is 100 times less H2 positive ions at 6.0 than 4.0. Weak organic acids released from peat are not strong enough to acidify frequently changed water down to the low end of what your target value is for your Heckels in the short time allowed.
It is worth obtaining a water pressure booster pump and if it doesn't improve the rejection rates it will at least maximize volume efficiency. I would also double check the calibration of your electronic EC/TDS meter. Be sure you perform all water tests well away from electrical equipment such as your aquarium lights. I have seen testing the same sample at the tank or in situ is often going to result in a spurious reading. The same sample of water tested at least 3 feet from electromagnetic fields will usually be much different and in a better way. This is advice I extend to electronic pH meter use as well.

When it is all said and done, you will have made a considerable improvements in making water more similar to their natural environment but Heckels are adaptable enough to still thrive in the kind of water you have been able to give them after all the new technology was put in place and I really don't think more is going to make a practical difference.
I know that obtaining strong acids, even highly diluted forms, is difficult in Singapore.
Strong acids are essential ingredients in the production of home made explosives. It is also a listed precursor chemical used to produce cocaine, heroin and methamphetamine and Singapore is just being proactive but there is also the practical matter of disposal of toxic materials. Even where the regulations are less stringent in some countries there is a system of "cradle to grave" custody trail which must be observed. It isn't that strict in the USA where every hardware store stocks Muriatic Acid, a dilute Hydrochloric acid solution in water. A one US Gallon container is only about $10(or $36 for maximum strength) and a gallon is enough to last through 10,000 or 20,000 gallons of pH adjusted water.

[jimg]

Jim, if the membrane you are using is a bog standard TF-1812 of some sort, then 45psi is somewhere near the low-end of the pressure range at which it should be operated. The quality and the quantity of the product water vs. the amount of wastewater are all much better at higher pressures. 100psi is the upper limit for these membranes, at which a 100gpd RO can (under ideal circumstances) produce up to 120 gallons a day. Those who are saying that low pressures are OK, want to sell you a replacement membrane a.s.a.p. If the pressure is right, quality membranes can go up to 4-5 years without any problems. My own 300gpd unit has been running for about 5 years, the feed water is around 360ppm, the product water is 2-6ppm, depending mainly on the temperature.

Illumnae,
A pressure gauge is a handy little piece of kit to have on every RO-unit. It should not cost more that 5-10 dollars to buy one and it's well worth it. Also, most good membranes have a rejection rate of 96-98% on average and again - with decent pressure on tap they can go up to 99.5%. It also depends on what sort of dissolved substances you your mains water contains.

N./

I use dow filmtec which are designed to be used at between 40 - 60 psi. As far as I always understood, temp in the 70's helps production and higher pressure can cause lower rejection rates or early membrane failure. I could be wrong though.

[Apistomaster]

I have the same experience as Jim, 340 ppm in and 5 to 10 PPM TDS out.
My unit is now about 6 years old running on the original membrane and the water pressure is about 45 psi. I would like a booster pump but I plan to include that when I upgrade to a high capacity RO Unit but I am not using enough RO water for a higher capacity unit to be justified. If I ever get a bunch of wild Red Spotted Greens I would buy the larger unit first.

[jimg]

I have the same experience as Jim, 340 ppm in and 5 to 10 PPM TDS out.
My unit is now about 6 years old running on the original membrane and the water pressure is about 45 psi. I would like a booster pump but I plan to include that when I upgrade to a high capacity RO Unit but I am not using enough RO water for a higher capacity unit to be justified. If I ever get a bunch of wild Red Spotted Greens I would buy the larger unit first.

I don't think you need a booster pump. When I get my wild reds from hans I may need more too!!

[illumnae]

I've got my TDS to ~60 and pH 5.7 now I'm soaking Ketapang leaves in the RO water barrel for 3-4 days prior to water change to get the water nice and brown and steeped in the "good stuff". The fish seem to be showing better colours and are less shy now.

Just need to drop the TDS by another ~20 and the pH by about 1 and I'm all set!