high ph killing rubber lipped pleco??

[asquirrel]

Hi Folks,

After I installed an upflow algae scrubber my PH went from 6.8 to 7.6. Maybe 8 sometimes. Been running this thing during the day for a year and then shut it off at night. However, over the last 6 months I've been running it all night long (with light off during the night). I had 4 cory cats (peppered, melini, albino, and emerald). Also one rubber lipped pleco. I've had these guys since 2015 approx. Pepper died last week from what looked to be a swollen gill flap. Tried antibiotics (Kanaplex) and it didn't help. Then I was thinking maybe it was gill flukes so I got some anti parasitical (API general cure) that I'm going to try on the rest of the fish. Pepper corycat died last week, just before I got the API general cure.

So this morning I wake up and I see my rubber lipped pleco lying on his back at the bottom of my tank. Oh sh . . . I flipped him over and he's alive. However, that doesn't mean he's good. He looks really dark. He usually hides during the daytime unless there is a water change so this is bad news.

My tank has been cycled for a few years and I changed about 50% of the water every 10 days. I checked the parameters today. PH - 7.5, Ammonia - 0, nitrites - 0, nitrates - 5 ppm. 20 gallon tank. Water temp varies between 75-80 (depends on what thermometer I use to check it).

My question is whether the raised PH could be harming the fish?
I went online to check the PH stats -

Rubber lipped pleco ph - 6-8
http://www.aquariumlife.net/profiles/pl ... 100074.asp
or
6.5 - 7.5
http://www.liveaquaria.com/product/1004 ... 0+837+1004

Emerald cory cat
ph 5-8
https://en.wikipedia.org/wiki/Emerald_catfish
Melini cory cat
ph 6-8
https://en.wikipedia.org/wiki/Corydoras_melini
albino cory cat
ph 6-8
http://animal-world.com/encyclo/fresh/catfish/acory.php

Any advice would be appreciated.

[Bas Pels]

pH 8 is not really high. Rubberlips - I will assume you mean Chaetostoma come from fast flowing waters, where normally the pH is around neutral.

However, I read you cured 2 deseases shortly after each other. Medicins are - generally speaking - not good for fish (but worse for the desease). Curing 2, perhaps without firt remouving the last traces of the first might have done the job. The killing, that is
firstly, because surviving a cure costs energy
secondly, because the medicins might have interacted with each other

While it is best not to need medicins, sometimes we do. But in such a case, we should be carefull about using them. Follow the instructions, and after thecure, remouve the traces. By a good double water change, by filtration over carbon or by using UV (many medicins are sensitive to UV)

Than, allow the fish a few weeks recovery

[pleco_breeder]

I doubt this being directly related to the algae scrubber unless it was being used as the only means of filtration. You don't mention what other forms of filter are on the tank, or the substrate depth, but I've seen issues caused by both when using algae scrubbers. Mostly because they're expected to be the only form of maintenance and other things get out of control.

While I personally think they're very effective at what they do, there are requirements which have to be met in order for them to be effective long term without causing the same problem they're intended to fix. After all, they are nothing more than a controlled form of eutrophication done in a way to allow easy access to nutrient removal.

A bit more in depth description of your tank and maintenance (including how often algae is removed) would be helpful in providing better advice.

Larry Vires

[dw1305]

Hi all,

After I installed an upflow algae scrubber my PH went from 6.8 to 7.6. Maybe 8 sometimes. Been running this thing during the day for a year and and then shut it off at night. However, over the last 6 months I've been running it all night long (with light off during the night).........

First of all commiserations on your losses.

Algal scrubber
Why an algal scrubber? and when you say you've been running it at night with the light off, do you mean that the water is passing over the scrubber, but the scrubber isn't illuminated? If it is the latter option the scrubber will be contributing to the bioload (using oxygen) when the lights are off, and you may have had low oxygen issues at night.

I'm a great fan of plants, and there isn't anything intrinsically wrong with an algal scrubber, but there are more efficient ways to add plants in a freshwater tank. Higher plants have greater potential for the removal of nutrients, the problem for marine aquarists is that there are only a few higher plants (Angiosperms), that occur as submerged marine aquatics (https://en.wikipedia.org/wiki/Zosteraceae).

pH
I'll assume that you didn't have other plants before you added the scrubber? In that case the change in pH is to do with the change in the CO2:O2 ratio, these changes are entirely normal in planted systems, whether natural water courses or aquariums.

It occurs because CO2 is depleted during photosynthesis, and usually some small proportion of CO2 goes into solution as carbonic acid (H2CO3), and this depresses the pH. Oxygen is a base (the hydroxide ion is really O-H). When you have plants they produce oxygen during photosynthesis and deplete CO2.

I agree with @pleco_breeder, I don't think it is a direct result of either pH change or the scrubber directly. Changes in pH, caused by changes in the CO2:O2 ratio, don't effect the alkalinity of the water, just the pH.

cheers Darrel

[pleco_breeder]

I started using algae scrubbers in my fish room about three years ago in order to research them and their effect on water quality, and can definitely say without doubt that they are beneficial. The problem comes in when they are expected to be a "miracle filter", as seems to be marketed. They do keep nutrient levels exceptionally low once finished seeding, but are incapable of handling sudden spikes. There is also an issue if nutrients are allowed to build without proper cleaning. I've spoke with several hobbyists that thought the scrubber was supposed to be all they would ever need, and several sellers have even stated that you won't need to do water changes anymore (only topping up with RO/DI).

There is definitely a place for the units, and I couldn't even keep emersed plants alive in some of my tanks before their installation because algaes would choke the roots, but a lot of the marketing of these units is far from being honest. They should only ever be used as a "part" of an effective maintenance strategy.

As an aside, I used a data logger on some of the tanks which I was using to test these. The pH swings were insignificant when compared to an equal amount of oxygenation for upflow types. For sump type, where water flowed across the screen from the outlet, there was literally no change. This is because the gasses are exchanged nearly immediately and is a part of most designs in order to maintain the gasses necessary to grow the algae as quickly as possible.

Larry Vires

[dw1305]

Hi all,
Thanks Larry (@pleco_breeder), that is really useful.

I've never used an algal scrubber, but the gas exchange bit makes perfect sense. Can I ask which algae you have on yours? I'd assumed that it is a green filamentous type? and do you have a photo?

cheers Darrel

[pleco_breeder]

Mine were broken down before leaving for Japan last year. Initially, it was a very dark green filamentous which only grew to about 1cm. After about six months of operation, it was as if the algae in the tank (not on the scrubbers) literally crashed. I'm talking sheets of dead diatom and brush algae literally falling off the walls. It was such a fast occurrence that it plugged my HMF's, which were running without problem previously, overnight. This happened in all 4 of the test systems over the course of about a month.

A couple weeks after the "crashes", the algae on the screens became the standard light green filamentous type. It wasn't a sudden change on the screens, and actually started at the top of the screens. This was surprising as I expected to see it at the bottoms first.

Particular interest was the water quality values during the test. There was never any sudden effect on pH or TDS. N, P, K, and Fe were tested consistently and never showed any sudden change till after the die-off. I assume this was because of the algaes in the tank acting as a nutrient sink and maintaining set values as they slowly died and released nutrients. After cleaning from the algae crashes, including the HMF's, all the values except Fe quickly dropped. Iron levels in my local water are consistently high, so I'm again assuming that it was being replenished by water changes at a rate faster than the algae were consuming it.

One of the test systems was equipped with a DIY coil denitrifier, and had consistently undetectable levels of nitrogen, even before adding the scrubber. This had no effect on algae growth on the scrubber. Never managed to come to any reliable hypothesis for the reason, but assumed it was feeding from trace levels below the range of my tests.

Larry Vires