How low is too low for KH

[Chuunofish]

Hi All

I use RO water in a medium planted and stocked 350ltr tank which is currently at 3dkh, everything seem happy and parameters are 0 ammonium, 0 nitrite, 0 nitrate and are consistent between my 15% weekly water changes. I have read stories about tank crashes and am concerned that the low KH could cause a minor issue to be a major wipe or am I just being paranoid, also I would be interested in peoples views on using liquid carbon plant food at these parameters?

[dw1305]

Hi all,

I use RO water in a medium planted and stocked 350ltr tank which is currently at 3dkh, everything seem happy and parameters are 0 ammonium, 0 nitrite, 0 nitrate and are consistent between my 15% weekly water changes. I have read stories about tank crashes and am concerned that the low KH could cause a minor issue to be a major wipe or am I just being paranoid, also I would be interested in peoples views on using liquid carbon plant food at these parameters?

Can we have a picture of the tank? and some details of filtration which filter, what filter media etc? It is difficult to judge "medium planted" and "medium stocked", every-one has different ideas.

In terms of using liquid carbon, then it won't improve plant growth if you really have low levels of nitrate. Plants can only make use of more carbon if their growth isn't limited by the level of another essential nutrient.

You will always have diurnal changes in pH level in soft water, when you have plants, due to changes in the relative proportions of dissolved oxygen and CO2. These happen in nature as well as in the tank. Personally I wouldn't be worried about having 3 dKH carbonate hardness as long as you keep up the water changes.

cheers Darrel

[2wheelsx2]

I agree with Darrel. Pics and more details of filtration, etc would be helpful. Are you using KH boosting media in your filter? Where I live on the southwest coast of Canada, our municipal water is basically rainfall and snow melt with a TDS of < 30 normally. In a 24 cycle, my planted tanks swing from 6.6 - 6.9 (my tanks all have a lot of Manzanita wood in them. I run crushed coral and oyster shells (chicken feed) in my filters to keep the KH up. I couldn't really tell you what my measurements are as I do one to two 50 - 75% wc a week in my tanks and have done so for years and eventually I just stopped worrying and change water.

[Chuunofish]

Filtration standard Juwel rio stack, foam and ceramic media full time with oase 650 biomaster canister filter again with foam and plastic balls operating 8 hrs per day. So possibly overkill on the filtration but you can never have too much can you????

[Chuunofish]

I agree with Darrel. Pics and more details of filtration, etc would be helpful. Are you using KH boosting media in your filter? Where I live on the southwest coast of Canada, our municipal water is basically rainfall and snow melt with a TDS of < 30 normally. In a 24 cycle, my planted tanks swing from 6.6 - 6.9 (my tanks all have a lot of Manzanita wood in them. I run crushed coral and oyster shells (chicken feed) in my filters to keep the KH up. I couldn't really tell you what my measurements are as I do one to two 50 - 75% wc a week in my tanks and have done so for years and eventually I just stopped worrying and change water.

No boosting agents, and water has same parameters day after change as day before a change all the zeros

[dw1305]

Hi all,
Tank looks good.

Filtration standard Juwel rio stack, foam and ceramic media full time with oase 650 biomaster canister filter again with foam and plastic balls operating 8 hrs per day. So possibly overkill on the filtration but you can never have too much can you????

I think we mainly tend to have more efficient biological filtration than other fish keepers. Biological filtration is limited by oxygen content and we also keep fish that often have a requirement for high oxygen levels and warm water.

When you say "operating 8 hrs per day", what do you actually mean?

same parameters day after change as day before a change all the zeros

I'm not too worried about nitrate levels, but there are technical difficulties in testing for nitrate and it is unlikely that you don't have any nitrate.

cheers Darrel

[Bas Pels]

I'm afraid the filter only works for 8 hours a day. That is not a good practise.

Filtration does two things to a tank - it remouves large debris, which is not really important to your fishes and it supports the NH3 the fish excrete -> NO2- -> NO3- by bacteria. This latter is relatively harmless, the other two are not.

Now the thing is, these bacteria both need oxygen for this process, and to survice. In fact, they are rather sensetive in that matter.

Putting the filtration off will result in a rapidly decrease of oxygenlevels in the filter, and these low levels of oxygen will kill the good bacteria.

Putting the filtration on in the morning will pour all the waste produced by killing them into the tank, where yoou don't want it.

Now, as this is your shedule, this schedule will have prevented the bacteria from developing colonies, that is, not many of them wil die at night, and therefore the filter can be put on harmlessly in the morning, but still - the netto effect is that where a filter is to help turn ammonia into nitrate, you on/off schedule will prevent your filter from doing so.

It is, therefore, better to keep the filter on.

[TwoTankAmin]

I ran a planted tank with pressurized co for over a decade and my KH was always 3-4 dg. I worried a great deal initially about the potential for a pH crash. I did the crushed coral in my filter for a while. Because of space considerations I ran my co2 through the intake of my Eheim canister and then out into the water with nothing to "help" with diffusion. I also did not want to use a pH controller to regulate CO2 flow. I was prepared to have an air pump on a time to come on at lights out and turn back on shortly before lights on.

I would get up a couple of times a night to test. I also tended to run a leanish mix of co2 in the the 50 gal tank. After a few weeks I realized i could leave the co2 on 24/7 as long as my bubble rate was 1/second or slightly less. There was never a pH crash in the decade + and this was one of my healthiest. Ultimately I tore the tank down because I was spending more time caring for the plants than the fish and I am, at heart, a fish keeper. I also learned I did not need the crushed coral and stopped it.



At my peak I had a dozen planted tanks (now down to 6). With the exception of the tank above, I have added Flourish Excel weekly after the water change to every one of my planted tanks. I have never seen any ill effects from this on either plants or fish. I also fertilize using the Tropica line of products and have for about 18 years. I also use the SeaChem liquid ferts (nitrogen, potassium and phosphorus) for planted tanks 75 gals. and up. In those tanks I use the Tropica Trace/Micronutrient product.

[Chuunofish]

The 8 hours for the oase 650 is because it is the second filter and used to supplement the juwel filter bioflow L stack as the standard juwel set up has less than 3x turnover for a 350ltr tank at 1000lph as well as only being specified for tanks upto 60cm. As this is a standard configuration for Juwel Rio 350 and I have had no response from Juwel as to why they under specify the filter unit in the Rio 350. I am also using a juwel oxyplus diffuser on the bioflow to ensure decent oxygenation

[dw1305]

Hi all,

The 8 hours for the oase 650 is because it is the second filter and used to supplement the juwel filter bioflow L stack as the standard juwel set up has less than 3x turnover for a 350ltr tank at 1000lph as well as only being specified for tanks upto 60cm.

OK, as the others have said, you need to leave the filter on all the time, or you can leave it off permanently and have an air-pump coming on for the period when the light is off.

The advantage of a planted tank is that plants are massively net oxygen producers (and nitrogen assimilators), but even then they contribute to the bioload at night, when they aren't photosynthesizing.

@Bas Pels and @TwoTankAmin are really experienced fish-keepers and breeders. I'm a pretty shoddy fish-keeper in comparison, so I need all the help I can get. Lots of water flow and plants make tank management easier.

cheers Darrel

[Chuunofish]

Thanks Darrel, any advice is much appreciated it's all relative as I am a noob with all the gear and no idea

[dw1305]

Hi all,

Thanks Darrel, any advice is much appreciated it's all relative as I am a noob with all the gear and no idea

You are more than welcome. I'm good with plants, but I'm not a great fish-keeper. I know there are people on the forum with a fantastic amount knowledge about fish-keeping, so if something is outside of the remit of my knowledge I'm going to ask them.

cheers Darrel

[Chuunofish]

Further update, have discovered a baby Oto circa 1cm long so must be getting something right. Apologies for the bad quality picture