Perfecting RO Water Preparation - Suggestions

[Branch]

After years of preparing my water using Tropic Marin Re-mineral I want to try and use a more stable and natural method. Although the current method keeps the PH around 7 - 7.5 the KH is generally around 1-2 which can be unstable especially when I'm away on holiday and water changes, 70% per week over two vacuums, are reduced. As I use 100% RO water and keep Wild Discus I would prefer to maintain a PH of around 6.5 to 7 however the important part is the KH which ideally should be around 3 - 6. My water is aged over two nights in a 20 Imp (bigger than US) Gallon water butt where I presently add the Re-Min however what would be the best natural alternative? peat (doesn't this cloud the water and also how much and what type?), crushed coral used for marine tanks? (again how much?) or anything else?
Thank you. B

[Second Hand Pat]

Can you measure TDS Branch?
Pat

[Branch]

Hi Pat, excuse me for putting this under the wrong heading i.e. food instead of water! Anyway my TDS is circa 230 us or 147 ppm correlating to a GH of 8.5. I can get the TDS down to under a 100 or 64ppm GH 3.7 but then I have no KH/buffer as the water is effectively pure RO. What I would like is an alternative to the Tropic Re- Min that maintains a suitable KH and PH (6.5 ish) without high TDS. Make sense?

[Second Hand Pat]

Yup but not sure you can do this by changing the mineral content. You are trying to buffer the KH a bit more. You might try a wee bit of crushed coral to maintain the KH. Another thought is more frequent water changes.
Pat

[Branch]

Okay Pat, I'm now doing more frequent but smaller water changes, 10 - 15 gallons every two days after vacuuming the substrate. If I add a bag of crushed coral (how much?) into my 20 gallon water butt used to age the water can I cease using the Tropic re-min as my RO water is PH 6.5 and 0 TDS so it only needs a buffer to prevent it crashing. What about a bag of peat? Thanks for you patience and moving the post across. B

[Second Hand Pat]

You will still need to remin your RO water Branch. The fish do need some minerals in the water IMO. When I was mostly using RO water I would add enough tap water for a TDS for 40. Then I was adding a remin product for a target of 100 TDS in my water change water. The wild discus and altums loved the water. Try the smaller water changes to see if that buffers your water. Why do you want to add peat? Are you keeping wilds or domestics?

Pat

[Branch]

Will continue to add the re-min Pat however our tap water has very high levels of nitrate so I'll not risk mixing it with the RO. TDS today around 100ppm. I have 2 Wild Blues, 3 Browns and 2 Heckels together with 6 tank domestics, including Snakeskins and Pigeon Bloods. I'd heard that peat was good for the water?

B

[DJW]

I think Tropic Marin contains some KH buffer as well as the general hardness minerals, so if thats the case the more you add the higher the pH will go. You could try adding less, up to a TDS of maybe 50 instead of 100 ppm. The pH should be lower, but keep in mind that when the pH is lower, it will tend to fall, which means you might need more frequent water changes. This all depends on stocking density (fish per gallon), with a lightly stocked tank being more steady.

You can't have lots of buffer and a low pH at the same time. This is a rule of water chemistry. (the only way around it is to inject CO2, but that is for plants, not fish)

Peat does two things: it adds tannins to the water, turning it a yellow-brown color, which makes it more like native habitat. It also lowers the pH when used with RO. You can get the tannins by adding Rooibos tea, which is easier to use than peat. Peat can be a bit of a hassle... and keeping a low pH tank is a balancing act that takes some practice and trial & error. I don't see much point in doing a lot of extra work to get a slightly lower pH. IMO you don't really get the benefit of inhibiting troublesome bacteria until the pH is below 6.

I use 100% RO and only add GH minerals to a TDS of 30-50 ppm. There is no buffer at all, but I change a lot of water. If you want to go a few days between water changes, you generally need some buffer, which means you have to settle for a higher pH.

Or you can use a handful of crushed coral in the filter. The idea is to find the right amount, so it slowly dissolves KH into the water at the same rate as the biofilter is consuming KH and acidifying the water.

[Branch]

Thanks for the input I'll give the peat a miss then. How much water do you change each week and what tank size, frequency etc? Would it be just as beneficial to use crushed coral on my water preparation butt (20 IMP Gallons) rather than adding it to the filter? If I work on maturing 20 Gallons with the coral how much would you think I need? a handful? weight? Thanks. B

[Second Hand Pat]

Most folks add it to the filter or tank. Best to start with a very small amount and test the KH to see if you need to change the amount of crushed coral.
Pat

[Branch]

Will do but in the water butt together with a reduced amount of Tropic re-min. Thanks. B

[Second Hand Pat]

Will do but in the water butt together with a reduced amount of Tropic re-min. Thanks. B

OK, but you are trying to keep the KH from dropping in the tank. Not the water change container. It is the biological functions of the fish which acidify the water and deplete the buffering of the KH.
Pat

[DJW]

Coral dissolves faster as the pH goes lower, so the coral is reacting against a falling pH in the tank. This is why it makes more sense to put a slow-release buffer like crushed coral in the tank, as Pat is suggesting, rather than in the water barrel. This method would be good for going on vacation. You could try 1/2 cup in the filter or in a media bag in a high flow area, then watch the pH. If the pH in the tank goes higher than the pH in the ageing barrel, there is too much coral. You want the new water to have the same or a little higher pH than the tank water when you do WCs. Some trial & error is needed because of all the variables.

If you want to increase the KH (and consequently the PH too) in the barrel ahead of time for water changes, you might as well use a buffer that dissolves right away, like potassium bicarbonate or baking soda. This method is very predictable since you can routinely make water with exactly the KH you want.

Each method has its own advantages. Crushed coral is more common. The method I use is different. When I feed the fish I add 1/2 cup of my lovely alkaline tap water to the tanks and that keeps the pH steady enough.

[Branch]

All sounds logical to me I will try to incorporate what you and Pat have advised. The Wild are all now feeding and look amazing however I'm facing another issue which I will post separately. Many thinks for yours and Pat's input. Even though I've kept discus for circa 25 years there's still a lot to learn. B

[Cosmo]

When I used to use 100% RO water I used commercial additives instead of natural (crushed coral) because it is easier to measure and get consistent results. I used Kent RO Right for Gh, Kent Ph Stable for Kh (NEVER add either of these directly to the tank!!), and Kent Discus Essentials for minerals etc. When I kept wilds I kept the Ph at 6.2, which, unfortunately did not allow me to get sufficient Kh and if I didn't do large daily water changes the water would crash within 24/36 hours. To stabilize the water would have required upping the TDS way into the hard water range, which would have at the same time raised the Ph. Best bet I found is to not use 100% RO water. At this point I do not use any at all but still add the Discus Essentials. If your tap water is unusable ( why?) they you need to up your RO production. Get hold of an Aquatec 8800, buy a second pressure vessel and two 150 gal membranes. If your source water pressure is sufficient you should be able to produce over 200gpd. All in all, however, unless you are talking breeding tanks aged tap water is your best bet - have you tried that and found it still unusable?